diff --git a/src/Add-on/twoD2threeD/Command_Curve2Polyline.ts b/src/Add-on/twoD2threeD/Command_Curve2Polyline.ts
index 797ae603c..b8322b022 100644
--- a/src/Add-on/twoD2threeD/Command_Curve2Polyline.ts
+++ b/src/Add-on/twoD2threeD/Command_Curve2Polyline.ts
@@ -280,30 +280,30 @@ export class Command_Curve2Polyline implements Command
     }
 }
 
-export function CurveInOCS(curve: Curve, Ocs: Matrix4, OcsInv: Matrix4): boolean
+export function CurveInOCS(curve: Curve, Ocs: Matrix4, OcsInv: Matrix4, zFuzz = 1e-3): boolean
 {
     if (curve instanceof Line)
     {
         let p = curve.StartPoint.applyMatrix4(OcsInv);
-        if (!equaln(p.z, 0, 1e-3)) return false;
+        if (!equaln(p.z, 0, zFuzz)) return false;
         p = curve.EndPoint.applyMatrix4(OcsInv);
-        if (!equaln(p.z, 0, 1e-3)) return false;
+        if (!equaln(p.z, 0, zFuzz)) return false;
         return true;
     }
     else if (curve instanceof Arc)
     {
-        return matrixIsCoplane(curve.OCS, Ocs, 1e-3);
+        return matrixIsCoplane(curve.OCS, Ocs, zFuzz);
     }
     else if (curve instanceof Polyline)
     {
-        if (matrixIsCoplane(curve.OCS, Ocs, 1e-3))
+        if (matrixIsCoplane(curve.OCS, Ocs, zFuzz))
             return true;
         else
         {
             let cus = curve.Explode();
             return cus.every(c =>
             {
-                return CurveInOCS(c, Ocs, OcsInv);
+                return CurveInOCS(c, Ocs, OcsInv, zFuzz);
             });
         }
     }
@@ -367,6 +367,10 @@ export function GroupCurves(curs: Curve[]): { ocs: Matrix4, cus: Curve[]; }[]
             }
             return true;
         });
+
+        if (cus.length === 0)
+            throw "对曲线分组失败,请勾选强制使用(当前或前视图)坐标系,或对二维图形进行Z轴归0(Z0)后重新操作!";
+
         curveGroup.push({ ocs, cus });
     }
     return curveGroup;