diff --git a/Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityVirtualBundleRequestOperation.cs b/Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityVirtualBundleRequestOperation.cs
new file mode 100644
index 00000000..1923bfd8
--- /dev/null
+++ b/Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityVirtualBundleRequestOperation.cs
@@ -0,0 +1,65 @@
+using UnityEngine.Networking;
+using UnityEngine;
+
+namespace YooAsset
+{
+    internal class UnityVirtualBundleRequestOperation : UnityWebRequestOperation
+    {
+        protected enum ESteps
+        {
+            None,
+            Download,
+            Done,
+        }
+
+        private readonly PackageBundle _bundle;
+        private readonly int _downloadSpeed;
+        private ESteps _steps = ESteps.None;
+
+        internal UnityVirtualBundleRequestOperation(PackageBundle packageBundle, int downloadSpeed, string url) : base(url)
+        {
+            _bundle = packageBundle;
+            _downloadSpeed = downloadSpeed;
+        }
+        internal override void InternalStart()
+        {
+            _steps = ESteps.Download;
+        }
+        internal override void InternalUpdate()
+        {
+            if (_steps == ESteps.None || _steps == ESteps.Done)
+                return;
+
+            if (_steps == ESteps.Download)
+            {
+                // 模拟下载进度
+                float progress = 0;
+                if (DownloadedBytes > 0)
+                    progress = DownloadedBytes / _bundle.FileSize;
+                long downloadBytes = (long)((double)_downloadSpeed * Time.deltaTime);
+                
+                Progress = progress;
+                DownloadProgress = progress;
+                DownloadedBytes += downloadBytes;
+                if (DownloadedBytes < _bundle.FileSize)
+                    return;
+
+                Progress = 1f;
+                DownloadProgress = 1f;
+                DownloadedBytes = _bundle.FileSize;
+
+                _steps = ESteps.Done;
+                Status = EOperationStatus.Succeed;
+            }
+        }
+        internal override void InternalWaitForAsyncComplete()
+        {
+            if (_steps != ESteps.Done)
+            {
+                _steps = ESteps.Done;
+                Status = EOperationStatus.Failed;
+                Error = $"Try load bundle {_bundle.BundleName} from remote !";
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityVirtualBundleRequestOperation.cs.meta b/Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityVirtualBundleRequestOperation.cs.meta
new file mode 100644
index 00000000..c59ceee4
--- /dev/null
+++ b/Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityVirtualBundleRequestOperation.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 9e71e850eded0da43906cb4f7cb75629
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/DefaultEditorFileSystem.cs b/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/DefaultEditorFileSystem.cs
index b4108bc2..88357b24 100644
--- a/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/DefaultEditorFileSystem.cs
+++ b/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/DefaultEditorFileSystem.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 
 namespace YooAsset
 {
@@ -7,6 +8,7 @@ namespace YooAsset
     /// </summary>
     internal class DefaultEditorFileSystem : IFileSystem
     {
+        protected readonly HashSet<string> _records = new HashSet<string>();
         protected string _packageRoot;
 
         /// <summary>
@@ -37,15 +39,25 @@ namespace YooAsset
         }
 
         #region 自定义参数
+        /// <summary>
+        /// 模拟虚拟下载模式
+        /// </summary>
+        public bool VirtualDownloadMode { private set; get; } = false;
+
+        /// <summary>
+        /// 模拟虚拟下载的网速（单位：字节）
+        /// </summary>
+        public int VirtualDownloadSpeed { private set; get; } = 1024;
+
         /// <summary>
         /// 异步模拟加载最小帧数
         /// </summary>
-        public int _asyncSimulateMinFrame = 1;
+        public int AsyncSimulateMinFrame { private set; get; } = 1;
 
         /// <summary>
         /// 异步模拟加载最大帧数
         /// </summary>
-        public int _asyncSimulateMaxFrame = 1;
+        public int AsyncSimulateMaxFrame { private set; get; } = 1;
         #endregion
 
         public DefaultEditorFileSystem()
@@ -73,7 +85,10 @@ namespace YooAsset
         }
         public virtual FSDownloadFileOperation DownloadFileAsync(PackageBundle bundle, DownloadFileOptions options)
         {
-            throw new System.NotImplementedException();
+            string mainURL = bundle.BundleName;
+            options.SetURL(mainURL, mainURL);
+            var downloader = new DownloadVirtualBundleOperation(this, bundle, options);
+            return downloader;
         }
         public virtual FSLoadBundleOperation LoadBundleFile(PackageBundle bundle)
         {
@@ -92,13 +107,21 @@ namespace YooAsset
 
         public virtual void SetParameter(string name, object value)
         {
-            if (name == FileSystemParametersDefine.ASYNC_SIMULATE_MIN_FRAME)
+            if (name == FileSystemParametersDefine.VIRTUAL_DOWNLOAD_MODE)
             {
-                _asyncSimulateMinFrame = Convert.ToInt32(value);
+                VirtualDownloadMode = Convert.ToBoolean(value);
+            }
+            else if (name == FileSystemParametersDefine.VIRTUAL_DOWNLOAD_SPEED)
+            {
+                VirtualDownloadSpeed = Convert.ToInt32(value);
+            }
+            else if (name == FileSystemParametersDefine.ASYNC_SIMULATE_MIN_FRAME)
+            {
+                AsyncSimulateMinFrame = Convert.ToInt32(value);
             }
             else if (name == FileSystemParametersDefine.ASYNC_SIMULATE_MAX_FRAME)
             {
-                _asyncSimulateMaxFrame = Convert.ToInt32(value);
+                AsyncSimulateMaxFrame = Convert.ToInt32(value);
             }
             else
             {
@@ -124,11 +147,21 @@ namespace YooAsset
         }
         public virtual bool Exists(PackageBundle bundle)
         {
-            return true;
+            if (VirtualDownloadMode)
+            {
+                return _records.Contains(bundle.BundleGUID);
+            }
+            else
+            {
+                return true;
+            }
         }
         public virtual bool NeedDownload(PackageBundle bundle)
         {
-            return false;
+            if (Belong(bundle) == false)
+                return false;
+
+            return Exists(bundle) == false;
         }
         public virtual bool NeedUnpack(PackageBundle bundle)
         {
@@ -165,6 +198,11 @@ namespace YooAsset
         }
 
         #region 内部方法
+        public void RecordDownloadFile(string bundleName)
+        {
+            if (_records.Contains(bundleName) == false)
+                _records.Add(bundleName);
+        }
         public string GetEditorPackageVersionFilePath()
         {
             string fileName = YooAssetSettingsData.GetPackageVersionFileName(PackageName);
@@ -182,12 +220,12 @@ namespace YooAsset
         }
         public int GetAsyncSimulateFrame()
         {
-            if (_asyncSimulateMinFrame > _asyncSimulateMaxFrame)
+            if (AsyncSimulateMinFrame > AsyncSimulateMaxFrame)
             {
-                _asyncSimulateMinFrame = _asyncSimulateMaxFrame;
+                AsyncSimulateMinFrame = AsyncSimulateMaxFrame;
             }
 
-            return UnityEngine.Random.Range(_asyncSimulateMinFrame, _asyncSimulateMaxFrame + 1);
+            return UnityEngine.Random.Range(AsyncSimulateMinFrame, AsyncSimulateMaxFrame + 1);
         }
         #endregion
     }
diff --git a/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/Operation/DEFSLoadBundleOperation.cs b/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/Operation/DEFSLoadBundleOperation.cs
index 8edfc97b..a2b5d295 100644
--- a/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/Operation/DEFSLoadBundleOperation.cs
+++ b/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/Operation/DEFSLoadBundleOperation.cs
@@ -6,6 +6,7 @@ namespace YooAsset
         protected enum ESteps
         {
             None,
+            CheckExist,
             DownloadFile,
             LoadAssetBundle,
             CheckResult,
@@ -14,6 +15,7 @@ namespace YooAsset
 
         private readonly DefaultEditorFileSystem _fileSystem;
         private readonly PackageBundle _bundle;
+        protected FSDownloadFileOperation _downloadFileOp;
         private int _asyncSimulateFrame;
         private ESteps _steps = ESteps.None;
 
@@ -24,19 +26,57 @@ namespace YooAsset
         }
         internal override void InternalStart()
         {
-            _steps = ESteps.DownloadFile;
+            _steps = ESteps.CheckExist;
+            _asyncSimulateFrame = _fileSystem.GetAsyncSimulateFrame();
         }
         internal override void InternalUpdate()
         {
             if (_steps == ESteps.None || _steps == ESteps.Done)
                 return;
 
+            if (_steps == ESteps.CheckExist)
+            {
+                if (_fileSystem.Exists(_bundle))
+                {
+                    DownloadProgress = 1f;
+                    DownloadedBytes = _bundle.FileSize;
+                    _steps = ESteps.LoadAssetBundle;
+                }
+                else
+                {
+                    _steps = ESteps.DownloadFile;
+                }
+            }
+
             if (_steps == ESteps.DownloadFile)
             {
-                _asyncSimulateFrame = _fileSystem.GetAsyncSimulateFrame();
-                DownloadProgress = 1f;
-                DownloadedBytes = _bundle.FileSize;
-                _steps = ESteps.LoadAssetBundle;
+                if (_downloadFileOp == null)
+                {
+                    DownloadFileOptions options = new DownloadFileOptions(int.MaxValue);
+                    _downloadFileOp = _fileSystem.DownloadFileAsync(_bundle, options);
+                    _downloadFileOp.StartOperation();
+                    AddChildOperation(_downloadFileOp);
+                }
+
+                if (IsWaitForAsyncComplete)
+                    _downloadFileOp.WaitForAsyncComplete();
+
+                _downloadFileOp.UpdateOperation();
+                DownloadProgress = _downloadFileOp.DownloadProgress;
+                DownloadedBytes = _downloadFileOp.DownloadedBytes;
+                if (_downloadFileOp.IsDone == false)
+                    return;
+
+                if (_downloadFileOp.Status == EOperationStatus.Succeed)
+                {
+                    _steps = ESteps.LoadAssetBundle;
+                }
+                else
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Failed;
+                    Error = _downloadFileOp.Error;
+                }
             }
 
             if (_steps == ESteps.LoadAssetBundle)
diff --git a/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/Operation/internal/DownloadVirutalBundleOperation.cs b/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/Operation/internal/DownloadVirutalBundleOperation.cs
new file mode 100644
index 00000000..5e29e1bc
--- /dev/null
+++ b/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/Operation/internal/DownloadVirutalBundleOperation.cs
@@ -0,0 +1,156 @@
+using UnityEngine;
+
+namespace YooAsset
+{
+    internal class DownloadVirtualBundleOperation : FSDownloadFileOperation
+    {
+        protected enum ESteps
+        {
+            None,
+            CheckExists,
+            CreateRequest,
+            CheckRequest,
+            TryAgain,
+            Done,
+        }
+
+        // 下载参数
+        protected readonly DefaultEditorFileSystem _fileSystem;
+        protected readonly DownloadFileOptions _options;
+        protected UnityVirtualBundleRequestOperation _unityDownloadFileOp;
+
+        protected int _requestCount = 0;
+        protected float _tryAgainTimer;
+        protected int _failedTryAgain;
+        private ESteps _steps = ESteps.None;
+
+
+        internal DownloadVirtualBundleOperation(DefaultEditorFileSystem fileSystem, PackageBundle bundle, DownloadFileOptions options) : base(bundle)
+        {
+            _fileSystem = fileSystem;
+            _options = options;
+            _failedTryAgain = options.FailedTryAgain;
+        }
+        internal override void InternalStart()
+        {
+            _steps = ESteps.CheckExists;
+        }
+        internal override void InternalUpdate()
+        {
+            if (_steps == ESteps.None || _steps == ESteps.Done)
+                return;
+
+            // 检测文件是否存在
+            if (_steps == ESteps.CheckExists)
+            {
+                if (_fileSystem.Exists(Bundle))
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Succeed;
+                }
+                else
+                {
+                    _steps = ESteps.CreateRequest;
+                }
+            }
+
+            // 创建下载器
+            if (_steps == ESteps.CreateRequest)
+            {
+                if (_options.IsValid() == false)
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Failed;
+                    Error = "Download file options is invalid !";
+                    Debug.Log(Error);
+                    return;
+                }
+
+                string url = GetRequestURL();
+                int speed = _fileSystem.VirtualDownloadSpeed;
+                _unityDownloadFileOp = new UnityVirtualBundleRequestOperation(Bundle, speed, url);
+                _unityDownloadFileOp.StartOperation();
+                _steps = ESteps.CheckRequest;
+            }
+
+            // 检测下载结果
+            if (_steps == ESteps.CheckRequest)
+            {
+                if (IsWaitForAsyncComplete)
+                    _unityDownloadFileOp.WaitForAsyncComplete();
+
+                // 因为并发数量限制，下载器可能被挂起！
+                if (_unityDownloadFileOp.Status == EOperationStatus.None)
+                    return;
+
+                _unityDownloadFileOp.UpdateOperation();
+                Progress = _unityDownloadFileOp.Progress;
+                DownloadedBytes = _unityDownloadFileOp.DownloadedBytes;
+                DownloadProgress = _unityDownloadFileOp.DownloadProgress;
+                if (_unityDownloadFileOp.IsDone == false)
+                    return;
+
+                if (_unityDownloadFileOp.Status == EOperationStatus.Succeed)
+                {
+                    _fileSystem.RecordDownloadFile(Bundle.BundleName);
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Succeed;
+                }
+                else
+                {
+                    if (IsWaitForAsyncComplete == false && _failedTryAgain > 0)
+                    {
+                        _steps = ESteps.TryAgain;
+                        YooLogger.Warning($"Failed download : {_unityDownloadFileOp.URL} Try again !");
+                    }
+                    else
+                    {
+                        _steps = ESteps.Done;
+                        Status = EOperationStatus.Failed;
+                        Error = _unityDownloadFileOp.Error;
+                        YooLogger.Error(Error);
+                    }
+                }
+            }
+
+            // 重新尝试下载
+            if (_steps == ESteps.TryAgain)
+            {
+                _tryAgainTimer += Time.unscaledDeltaTime;
+                if (_tryAgainTimer > 1f)
+                {
+                    _tryAgainTimer = 0f;
+                    _failedTryAgain--;
+                    Progress = 0f;
+                    DownloadProgress = 0f;
+                    DownloadedBytes = 0;
+                    _steps = ESteps.CreateRequest;
+                }
+            }
+        }
+        internal override void InternalWaitForAsyncComplete()
+        {
+            while (true)
+            {
+                if (ExecuteWhileDone())
+                {
+                    _steps = ESteps.Done;
+                    break;
+                }
+            }
+        }
+
+        /// <summary>
+        /// 获取网络请求地址
+        /// </summary>
+        protected string GetRequestURL()
+        {
+            // 轮流返回请求地址
+            _requestCount++;
+            if (_requestCount % 2 == 0)
+                return _options.FallbackURL;
+            else
+                return _options.MainURL;
+        }
+    }
+}
\ No newline at end of file
diff --git a/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/Operation/internal/DownloadVirutalBundleOperation.cs.meta b/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/Operation/internal/DownloadVirutalBundleOperation.cs.meta
new file mode 100644
index 00000000..fe0f5b42
--- /dev/null
+++ b/Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/Operation/internal/DownloadVirutalBundleOperation.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: f043dc0e0f147334380cfd0720636544
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/Assets/YooAsset/Runtime/FileSystem/FileSystemParametersDefine.cs b/Assets/YooAsset/Runtime/FileSystem/FileSystemParametersDefine.cs
index b93f2384..df96122a 100644
--- a/Assets/YooAsset/Runtime/FileSystem/FileSystemParametersDefine.cs
+++ b/Assets/YooAsset/Runtime/FileSystem/FileSystemParametersDefine.cs
@@ -17,6 +17,8 @@ namespace YooAsset
         public const string DOWNLOAD_MAX_REQUEST_PER_FRAME = "DOWNLOAD_MAX_REQUEST_PER_FRAME";
         public const string RESUME_DOWNLOAD_MINMUM_SIZE = "RESUME_DOWNLOAD_MINMUM_SIZE";
         public const string RESUME_DOWNLOAD_RESPONSE_CODES = "RESUME_DOWNLOAD_RESPONSE_CODES";
+        public const string VIRTUAL_DOWNLOAD_MODE = "ENABLE_VIRTUAL_DOWNLOAD";
+        public const string VIRTUAL_DOWNLOAD_SPEED = "VIRTUAL_DOWNLOAD_MAX_SPEED";
         public const string ASYNC_SIMULATE_MIN_FRAME = "ASYNC_SIMULATE_MIN_FRAME";
         public const string ASYNC_SIMULATE_MAX_FRAME = "ASYNC_SIMULATE_MAX_FRAME";
         public const string COPY_BUILDIN_PACKAGE_MANIFEST = "COPY_BUILDIN_PACKAGE_MANIFEST";