diff --git a/src/Geometry/SpaceParse/ClampSpaceParse.ts b/src/Geometry/SpaceParse/ClampSpaceParse.ts
index bffb71a76..dc71c67b5 100644
--- a/src/Geometry/SpaceParse/ClampSpaceParse.ts
+++ b/src/Geometry/SpaceParse/ClampSpaceParse.ts
@@ -27,8 +27,14 @@ export class ClampSpaceParse extends ISpaceParse
             let splitType: SplitType = ConverBoardTypeToSpaceType(boardType);
             let boardBoxCol = this.ParseBoardBox(boards, splitType);
 
-            if (boardType === BoardType.Behind && this.m_BoardMap.size > 1)
-                boardBoxCol = [arrayLast(boardBoxCol)];
+            //#IWFYY
+            if (boardType === BoardType.Behind && this.m_BoardMap.size > 1 && boardBoxCol.length > 1)
+            {
+                let clampBox = boardBoxCol[0].clampSpace(boardBoxCol[1], splitType);
+                let size = clampBox.getSize(new Vector3());
+                if (size.y > 2440)
+                    boardBoxCol = [arrayLast(boardBoxCol)];
+            }
 
             if (boardBoxCol.length > 1)
             {