diff --git a/Source/GrasscutterTools/Forms/FormActivityEditor.cs b/Source/GrasscutterTools/Forms/FormActivityEditor.cs
index f09d257..b22cf5f 100644
--- a/Source/GrasscutterTools/Forms/FormActivityEditor.cs
+++ b/Source/GrasscutterTools/Forms/FormActivityEditor.cs
@@ -36,7 +36,7 @@ namespace GrasscutterTools.Forms
     {
         #region - 成员 -
 
-        private List<ActivityConfigItem> ActivityConfigItems;
+        private List<ActivityConfigItem> ActivityConfigItems = new List<ActivityConfigItem>();
 
         #endregion - 成员 -