diff --git a/src/Editor/GetRectServices.ts b/src/Editor/GetRectServices.ts
index e73401262..4bfca7538 100644
--- a/src/Editor/GetRectServices.ts
+++ b/src/Editor/GetRectServices.ts
@@ -58,6 +58,7 @@ export class GetRectPointServices
 
             let ucsInv = app.m_Editor.UCSMatrixInv;
             let basePointUCS = basePoint.clone().applyMatrix4(ucsInv);
+            basePointUCS.z = 0;
 
             let signX = 1;
             let signY = 1;
@@ -116,6 +117,7 @@ export class GetRectPointServices
 
                         p2UCS.x = basePointUCS.x + this.dynPrompt.Width * signX;
                         p2UCS.y = basePointUCS.y + this.dynPrompt.Height * signY;
+                        p2UCS.z = 0;
 
                         this.UpdateDynPrompt(basePointUCS, p2UCS);
                     }
@@ -131,6 +133,7 @@ export class GetRectPointServices
                 signY = Math.sign(res.Point2UCS.y - res.Point1UCS.y);
                 res.Point2UCS.x = res.Point1UCS.x + signX * this.dynPrompt.Width;
                 res.Point2UCS.y = res.Point1UCS.y + signY * this.dynPrompt.Height;
+                res.Point2UCS.z = 0;
 
                 res.Point1WCS = basePoint;
                 res.Point2WCS = res.Point2UCS.clone().applyMatrix4(app.m_Editor.UCSMatrix);
diff --git a/src/Geometry/GeUtils.ts b/src/Geometry/GeUtils.ts
index 2763a30c3..44f3654f2 100644
--- a/src/Geometry/GeUtils.ts
+++ b/src/Geometry/GeUtils.ts
@@ -1,4 +1,4 @@
-import { Box3, BufferGeometry, Geometry, Matrix4, Object3D, Vector, Vector2, Vector3, Line, Mesh } from 'three';
+import { Box3, BufferGeometry, Geometry, Line, Matrix4, Mesh, Object3D, Vector, Vector2, Vector3 } from 'three';
 import { ToFixed } from '../Common/Utils';
 import { Matrix2 } from './Matrix2';
 
@@ -138,6 +138,12 @@ export function isParallelTo(v1: Vector3, v2: Vector3): boolean
     return v1.clone().cross(v2).lengthSq() < 1e-8;
 }
 
+//垂直向量
+export function isPerpendicularityTo(v1: Vector3, v2: Vector3)
+{
+    return equaln(v1.dot(v2), 0, 1e-8);
+}
+
 export function ptToString(v: Vector3, fractionDigits: number = 3): string
 {
     return v.toArray().map(o => ToFixed(o, fractionDigits)).join(",");
diff --git a/src/GraphicsSystem/Viewer.ts b/src/GraphicsSystem/Viewer.ts
index f218f6911..073add795 100644
--- a/src/GraphicsSystem/Viewer.ts
+++ b/src/GraphicsSystem/Viewer.ts
@@ -1,4 +1,4 @@
-import { EffectComposer, Matrix4, Object3D, OutlinePass, RenderPass, Scene, Vector2, Vector3, WebGLRenderer, SMAAPass } from 'three';
+import { EffectComposer, Matrix4, Object3D, OutlinePass, RenderPass, Scene, SMAAPass, Vector2, Vector3, WebGLRenderer } from 'three';
 import * as xaop from 'xaop';
 import { end } from 'xaop';
 import { app } from '../ApplicationServices/Application';
@@ -7,12 +7,12 @@ import { Database } from '../DatabaseServices/Database';
 import { Entity } from '../DatabaseServices/Entity';
 import { GenerateRaycaster } from '../Editor/PointPick';
 import { CheckFilter } from '../Editor/SelectFilter';
-import { cZeroVec, GetBox, GetBoxArr } from '../Geometry/GeUtils';
+import { userConfig } from '../Editor/UserConfig';
+import { cZeroVec, GetBox, GetBoxArr, isPerpendicularityTo } from '../Geometry/GeUtils';
 import { PlaneExt } from '../Geometry/Plane';
 import { CameraUpdate } from './CameraUpdate';
 import { GripScene } from './GripScene';
 import { PreViewer } from './PreViewer';
-import { userConfig } from '../Editor/UserConfig';
 
 //导入其他js模块
 require("three-CopyShader");
@@ -186,13 +186,18 @@ export class Viewer
             this.m_Render.render(this.Scene, this.Camera);
     }
 
-    ScreenToWorld(pt: Vector3, planNormal?: Vector3, constant?: number | Vector3)
+    ScreenToWorld(pt: Vector3, planNormal?: Vector3, constant?: Vector3)
     {
+        if (!constant)
+            constant = new Vector3().setFromMatrixColumn(app.m_Editor.UCSMatrix, 3);
+        if (!planNormal)
+            planNormal = new Vector3().setFromMatrixColumn(app.m_Editor.UCSMatrix, 2);
+
+        if (isPerpendicularityTo(this.m_CameraCtrl.Direction, planNormal))
+            planNormal = this.m_CameraCtrl.Direction;
+
         //变换和求交点
-        let plan = new PlaneExt(
-            (planNormal === undefined) ? new Vector3().setFromMatrixColumn(app.m_Editor.UCSMatrix, 2) : planNormal,
-            (constant === undefined) ? new Vector3().setFromMatrixColumn(app.m_Editor.UCSMatrix, 3) : constant
-        );
+        let plan = new PlaneExt(planNormal, constant);
         let raycaster = GenerateRaycaster(pt, this);
         plan.intersectRay(raycaster.ray, pt, true);
         return pt;