diff --git a/OpenUtau.Core/DocManager.cs b/OpenUtau.Core/DocManager.cs
index 96b50100d..e7f0abd25 100644
--- a/OpenUtau.Core/DocManager.cs
+++ b/OpenUtau.Core/DocManager.cs
@@ -80,7 +80,7 @@ public void SearchAllPlugins() {
                 if (File.Exists(oldBuiltin)) {
                     File.Delete(oldBuiltin);
                 }
-                files.AddRange(Directory.EnumerateFiles(PathManager.Inst.PluginsPath, "*.dll", SearchOption.AllDirectories));
+                SearchPluginInternal(PathManager.Inst.PluginsPath, files);
             } catch (Exception e) {
                 Log.Error(e, "Failed to search plugins.");
             }
@@ -118,6 +118,16 @@ public void SearchAllPlugins() {
             stopWatch.Stop();
             Log.Information($"Search all plugins: {stopWatch.Elapsed}");
         }
+        private void SearchPluginInternal(string path, List<string> result) {
+            if (Directory.EnumerateFiles(path, "plugin.txt", SearchOption.TopDirectoryOnly).Any()) {
+                return;
+            }
+            result.AddRange(Directory.EnumerateFiles(path, "*.dll", SearchOption.TopDirectoryOnly));
+            var directories = Directory.EnumerateDirectories(path, "*", SearchOption.TopDirectoryOnly);
+            foreach (var directory in directories) {
+                SearchPluginInternal(directory, result);
+            }
+        }
 
         #region Command Queue