diff --git a/src/DatabaseServices/Arc.ts b/src/DatabaseServices/Arc.ts
index 4ba0139a2..dd606c084 100644
--- a/src/DatabaseServices/Arc.ts
+++ b/src/DatabaseServices/Arc.ts
@@ -384,8 +384,8 @@ export class Arc extends Curve
         //用圆心和其中一个点求距离得到半径：  
         this.m_Radius = this.m_Center.distanceTo(pt1);
         //起始角度 端点角度
-        this.m_StartAngle = this.getangle(pt1, this.m_Center);
-        this.m_EndAngle = this.getangle(pt3, this.m_Center);
+        this.m_StartAngle = angle(pt1.clone().sub(this.Center));
+        this.m_EndAngle = angle(pt3.clone().sub(this.Center));
         //求出向量p1->p2,p1->p3
         let p1 = new Vector3(0, 0, 0);
         p1.x = pt2.x - pt1.x;
@@ -404,13 +404,6 @@ export class Arc extends Curve
         }
     }
 
-    getangle(pt1: Vector3, pt2: Vector3)
-    {
-        let x = pt1.x - pt2.x;
-        let y = pt1.y - pt2.y;
-        return Math.atan2(y, x);
-    }
-
     InitDrawObject(renderType: RenderType = RenderType.Wireframe): THREE.Line
     {
         let geo = new THREE.Geometry();