diff --git a/src/GraphicsSystem/Viewer.ts b/src/GraphicsSystem/Viewer.ts
index 43b780471..6347760ae 100644
--- a/src/GraphicsSystem/Viewer.ts
+++ b/src/GraphicsSystem/Viewer.ts
@@ -1,5 +1,5 @@
 import * as THREE from 'three';
-import { Vector3 } from 'three';
+import { Vector3, OrthographicCamera } from 'three';
 import * as xaop from 'xaop';
 import { end } from 'xaop';
 import { Database } from '../DatabaseServices/Database';
@@ -208,7 +208,8 @@ export class Viewer
             x: (ptVcs.x / this.Width) * 2 - 1,   //-1 到 1  所以 (x-(w/2))/(w/2) =>
             y: - (ptVcs.y / this.Height) * 2 + 1 //y轴相反
         }, this.Camera);
-        raycaster.ray.origin.sub(raycaster.ray.direction.clone().multiplyScalar(1e9));
+        if (this.Camera instanceof OrthographicCamera)
+            raycaster.ray.origin.sub(raycaster.ray.direction.clone().multiplyScalar(1e9));
         return raycaster;
     }