diff --git a/src/DatabaseServices/Polyline.ts b/src/DatabaseServices/Polyline.ts
index a097fc348..222d419dd 100644
--- a/src/DatabaseServices/Polyline.ts
+++ b/src/DatabaseServices/Polyline.ts
@@ -1019,15 +1019,9 @@ export class Polyline extends Curve
         let pts = shape.getPoints(50).map(Vec2DTo3D);
         let plObj = en as THREE.Line;
         let geo = plObj.geometry as BufferGeometry;
-        if (pts.length <= geo.drawRange.count && geo.drawRange.count !== Infinity)
+        if (!BufferGeometryUtils.UpdatePts(geo, pts))
         {
-            BufferGeometryUtils.UpdatePts(geo, pts);
-            geo.drawRange.count = pts.length;
-        }
-        else
-        {
-            geo = BufferGeometryUtils.CreateFromPts(pts);
-            updateGeometry(plObj, geo);
+            updateGeometry(plObj, BufferGeometryUtils.CreateFromPts(pts));
         }
     }
     GetObjectSnapPoints(
diff --git a/src/Geometry/BufferGeometryUtils.ts b/src/Geometry/BufferGeometryUtils.ts
index 589a3f819..2e912a949 100644
--- a/src/Geometry/BufferGeometryUtils.ts
+++ b/src/Geometry/BufferGeometryUtils.ts
@@ -11,11 +11,23 @@ export namespace BufferGeometryUtils
         return geo;
     }
 
-    export function UpdatePts(geo: BufferGeometry, pts: Vector3[])
+    /**
+     * 更新BufferGeometry的顶点
+     * @param geo 
+     * @param pts 
+     * @returns 当成功时返回true,更新失败时返回false
+     */
+    export function UpdatePts(geo: BufferGeometry, pts: Vector3[]): boolean
     {
         let bf = geo.getAttribute("position") as BufferAttribute;
-        bf.copyVector3sArray(pts);
-        bf.needsUpdate = true;
+        if (bf.count >= pts.length)
+        {
+            bf.copyVector3sArray(pts);
+            bf.needsUpdate = true;
+            geo.drawRange.count = pts.length;
+            return true;
+        }
+        return false;
     }
 
     let arrowGeometry: ShapeGeometry;