diff --git a/Assets/YooAsset/Runtime/ResourcePackage/Operation/ClearAllBundleFilesOperation.cs b/Assets/YooAsset/Runtime/ResourcePackage/Operation/ClearAllBundleFilesOperation.cs
index e332ab9..3a06b68 100644
--- a/Assets/YooAsset/Runtime/ResourcePackage/Operation/ClearAllBundleFilesOperation.cs
+++ b/Assets/YooAsset/Runtime/ResourcePackage/Operation/ClearAllBundleFilesOperation.cs
@@ -45,6 +45,12 @@ namespace YooAsset
 
             if (_steps == ESteps.ClearFileSystemA)
             {
+                if (_fileSystemA == null)
+                {
+                    _steps = ESteps.ClearFileSystemB;
+                    return;
+                }
+
                 if (_clearAllBundleFilesOpA == null)
                     _clearAllBundleFilesOpA = _fileSystemA.ClearAllBundleFilesAsync();
 
diff --git a/Assets/YooAsset/Runtime/ResourcePackage/Operation/ClearUnusedBundleFilesOperation.cs b/Assets/YooAsset/Runtime/ResourcePackage/Operation/ClearUnusedBundleFilesOperation.cs
index f7862d0..10e7782 100644
--- a/Assets/YooAsset/Runtime/ResourcePackage/Operation/ClearUnusedBundleFilesOperation.cs
+++ b/Assets/YooAsset/Runtime/ResourcePackage/Operation/ClearUnusedBundleFilesOperation.cs
@@ -45,6 +45,12 @@ namespace YooAsset
 
             if (_steps == ESteps.ClearFileSystemA)
             {
+                if (_fileSystemA == null)
+                {
+                    _steps = ESteps.ClearFileSystemB;
+                    return;
+                }
+
                 if (_clearUnusedBundleFilesOpA == null)
                     _clearUnusedBundleFilesOpA = _fileSystemA.ClearUnusedBundleFilesAsync(_impl.ActiveManifest);
 
diff --git a/Assets/YooAsset/Runtime/ResourcePackage/Operation/InitializationOperation.cs b/Assets/YooAsset/Runtime/ResourcePackage/Operation/InitializationOperation.cs
index 22cc9b2..c69752f 100644
--- a/Assets/YooAsset/Runtime/ResourcePackage/Operation/InitializationOperation.cs
+++ b/Assets/YooAsset/Runtime/ResourcePackage/Operation/InitializationOperation.cs
@@ -201,14 +201,6 @@ namespace YooAsset
 
             if (_steps == ESteps.CreateFileSystem)
             {
-                if (_parameters.BuildinFileSystemParameters == null)
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                    Error = "Buildin file system parameters is null";
-                    return;
-                }
-
                 if (_parameters.CacheFileSystemParameters == null)
                 {
                     _steps = ESteps.Done;
@@ -217,6 +209,19 @@ namespace YooAsset
                     return;
                 }
 
+                if (_parameters.BuildinFileSystemParameters != null)
+                {
+                    _impl.BuildinFileSystem = PlayModeHelper.CreateFileSystem(_impl.PackageName, _parameters.BuildinFileSystemParameters);
+                    if (_impl.BuildinFileSystem == null)
+                    {
+                        _steps = ESteps.Done;
+                        Status = EOperationStatus.Failed;
+                        Error = "Failed to create buildin file system";
+                        return;
+                    }
+                    return;
+                }
+
                 if (_parameters.DeliveryFileSystemParameters != null)
                 {
                     _impl.DeliveryFileSystem = PlayModeHelper.CreateFileSystem(_impl.PackageName, _parameters.DeliveryFileSystemParameters);
@@ -229,15 +234,6 @@ namespace YooAsset
                     }
                 }
 
-                _impl.BuildinFileSystem = PlayModeHelper.CreateFileSystem(_impl.PackageName, _parameters.BuildinFileSystemParameters);
-                if (_impl.BuildinFileSystem == null)
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                    Error = "Failed to create buildin file system";
-                    return;
-                }
-
                 _impl.CacheFileSystem = PlayModeHelper.CreateFileSystem(_impl.PackageName, _parameters.CacheFileSystemParameters);
                 if (_impl.CacheFileSystem == null)
                 {
@@ -252,6 +248,13 @@ namespace YooAsset
 
             if (_steps == ESteps.InitBuildinFileSystem)
             {
+                // 注意：内置文件系统可以为空
+                if (_impl.BuildinFileSystem == null)
+                {
+                    _steps = ESteps.InitDeliveryFileSystem;
+                    return;
+                }
+
                 if (_initBuildinFileSystemOp == null)
                     _initBuildinFileSystemOp = _impl.BuildinFileSystem.InitializeFileSystemAsync();
 
diff --git a/Assets/YooAsset/Runtime/ResourcePackage/PlayMode/HostPlayModeImpl.cs b/Assets/YooAsset/Runtime/ResourcePackage/PlayMode/HostPlayModeImpl.cs
index 4344371..4daf812 100644
--- a/Assets/YooAsset/Runtime/ResourcePackage/PlayMode/HostPlayModeImpl.cs
+++ b/Assets/YooAsset/Runtime/ResourcePackage/PlayMode/HostPlayModeImpl.cs
@@ -7,7 +7,7 @@ namespace YooAsset
     internal class HostPlayModeImpl : IPlayMode, IBundleQuery
     {
         public readonly string PackageName;
-        public IFileSystem BuildinFileSystem { set; get; }
+        public IFileSystem BuildinFileSystem { set; get; } //可以为空！
         public IFileSystem DeliveryFileSystem { set; get; } //可以为空！
         public IFileSystem CacheFileSystem { set; get; }
 
@@ -118,7 +118,7 @@ namespace YooAsset
             if (packageBundle == null)
                 throw new Exception("Should never get here !");
 
-            if (BuildinFileSystem.Belong(packageBundle))
+            if (BuildinFileSystem != null && BuildinFileSystem.Belong(packageBundle))
             {
                 BundleInfo bundleInfo = new BundleInfo(BuildinFileSystem, packageBundle);
                 return bundleInfo;