diff --git a/examples/line/path/demo/road_light.js b/examples/line/path/demo/road_light.js
index 6a3e19d77d..743ce809b4 100644
--- a/examples/line/path/demo/road_light.js
+++ b/examples/line/path/demo/road_light.js
@@ -1,5 +1,10 @@
-import { Scene, LineLayer } from '@antv/l7';
-import { Mapbox } from '@antv/l7-maps';
+import {
+  Scene,
+  LineLayer
+} from '@antv/l7';
+import {
+  Mapbox
+} from '@antv/l7-maps';
 
 const scene = new Scene({
   id: 'map',
diff --git a/packages/layers/src/utils/__tests__/extrude_polyline.spec.ts b/packages/layers/src/utils/__tests__/extrude_polyline.spec.ts
index c2ce9a7eb7..9cea6c49ce 100644
--- a/packages/layers/src/utils/__tests__/extrude_polyline.spec.ts
+++ b/packages/layers/src/utils/__tests__/extrude_polyline.spec.ts
@@ -18,6 +18,6 @@ describe('extrude polyline', () => {
       coord[1] = lat;
     });
     const mesh = extrude.extrude(coords);
-    expect(mesh.indices.length).toBe(12);
+    expect(mesh.indices.length).toBe(6);
   });
 });
diff --git a/packages/layers/src/utils/extrude_polyline.ts b/packages/layers/src/utils/extrude_polyline.ts
index e44e0bf972..4c0a668e2e 100644
--- a/packages/layers/src/utils/extrude_polyline.ts
+++ b/packages/layers/src/utils/extrude_polyline.ts
@@ -34,12 +34,17 @@ function isPointEqual(a: vec2, b: vec2) {
 }
 
 function getArrayUnique(matrix: number[][]) {
-  const result: number[][] = [];
-  matrix.map((item) => {
-    item.sort((a, b) => b - a);
-    result.push(item);
-  });
-  return result;
+  const map = new Map();
+  for (let i = 0; i < matrix.length; i++) {
+    const key = matrix[0].toString() + '-' + matrix[1].toString();
+    if (map.get(key)) {
+      matrix.splice(i, 1);
+      i++;
+    } else {
+      map.set(key, key);
+    }
+  }
+  return matrix;
 }
 
 export interface IExtrudeLineOption {