diff --git a/__test__/Polyline/__snapshots__/polyline.test.ts.snap b/__test__/Polyline/__snapshots__/polyline.test.ts.snap
index 6151674be..738e3f058 100644
--- a/__test__/Polyline/__snapshots__/polyline.test.ts.snap
+++ b/__test__/Polyline/__snapshots__/polyline.test.ts.snap
@@ -1,5 +1,13 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`多段线 优化参数在端点上的时候 1`] = `
+Vector3 {
+  "x": 0,
+  "y": 0,
+  "z": 0,
+}
+`;
+
 exports[`多段线 最近点精度 1`] = `
 Vector3 {
   "x": 1.987500976448074,
diff --git a/__test__/Polyline/polyline.test.ts b/__test__/Polyline/polyline.test.ts
index 0c7cd6552..c726e0371 100644
--- a/__test__/Polyline/polyline.test.ts
+++ b/__test__/Polyline/polyline.test.ts
@@ -486,4 +486,16 @@ describe('多段线', () =>
 
         expect(cp).toMatchSnapshot();
     });
+
+    test('优化参数在端点上的时候', () =>
+    {
+        let pl = new Polyline();
+        pl.AddVertexAt(0, new Vector2(0, 0));
+        pl.AddVertexAt(1, new Vector2(5, 0));
+        pl.AddVertexAt(2, new Vector2(5, 5));
+        pl.CloseMark = true;
+
+        let p = pl.GetPointAtParam(3);
+        expect(p).toMatchSnapshot();
+    });
 })
diff --git a/src/DatabaseServices/Polyline.ts b/src/DatabaseServices/Polyline.ts
index 9e5e9408b..86c4576b5 100644
--- a/src/DatabaseServices/Polyline.ts
+++ b/src/DatabaseServices/Polyline.ts
@@ -267,11 +267,11 @@ export class Polyline extends Curve
      */
     GetPointAtParam(param: number): Vector3
     {
+        if (param === Math.floor(param))
+            return Vec2DTo3D(this.GetPoint2dAt(FixIndex(param, this.NumberOfVertices))).applyMatrix4(this.OCS);
         let cu: Curve = this.GetCurveAtParam(param);
         if (cu)
-        {
             return cu.GetPointAtParam(this.GetCurveParamAtParam(param));
-        }
         return undefined;
     }
 
diff --git a/src/GraphicsSystem/OffestPolyline.ts b/src/GraphicsSystem/OffestPolyline.ts
index 22d108009..00e067d41 100644
--- a/src/GraphicsSystem/OffestPolyline.ts
+++ b/src/GraphicsSystem/OffestPolyline.ts
@@ -12,7 +12,6 @@ import { equal, equaln } from "../Geometry/GeUtils";
 import { EBox, SortEntityByBox } from "../Geometry/SortEntityByBox";
 import { IsPtsAllOutOrOnReg } from "./BoolOperateUtils";
 import { IntersectOption } from "./IntersectWith";
-import { testContours, testCurve } from "../Add-on/testEntity/TestCurve";
 
 interface offestRes
 {
@@ -42,21 +41,16 @@ export class PolyOffestUtil
         let expCus = this.m_Polyline.Explode();
         let offres = this.OffestCurve(expCus, this.m_OffestDist);
 
-
         // console.time("join")
         this.TrimAndBuildContour(offres);
 
         for (let i = 0, count = this.m_Polyline.EndParam; i <= count; i++)
         {
             if (i === count && this.m_Polyline.IsClose)
-            {
                 break;
-            }
-            let center = Vec2DTo3D(this.m_Polyline.GetPoint2dAt(i)).applyMatrix4(this.m_Polyline.OCS);
-            let cir = new Circle(center, this.m_AbsDist);
+            let cir = new Circle(this.m_Polyline.GetPointAtParam(i), this.m_AbsDist);
             this.m_Contours.push(Contour.CreateContour([cir]));
         }
-        // testContours(this.m_Contours);
         // console.timeEnd("join")
         //裁剪
         let { boxCurves, outputCus } = this.trimByContours(this.m_RetCurves);