diff --git a/PPOCRLabel/libs/canvas.py b/PPOCRLabel/libs/canvas.py
index d5662ac79a85c07c79ed2b7df315f338a229535c..6ac1f28b85e65c3776d310136352b70c45628db6 100644
--- a/PPOCRLabel/libs/canvas.py
+++ b/PPOCRLabel/libs/canvas.py
@@ -704,8 +704,9 @@ class Canvas(QWidget):
 
     def keyPressEvent(self, ev):
         key = ev.key()
-        shapesBackup = []
         shapesBackup = copy.deepcopy(self.shapes)
+        if len(shapesBackup) == 0:
+            return
         self.shapesBackups.pop()
         self.shapesBackups.append(shapesBackup)
         if key == Qt.Key_Escape and self.current: