diff --git a/snake.py b/snake.py
index ff1b33f..3a00491 100644
--- a/snake.py
+++ b/snake.py
@@ -63,7 +63,8 @@ while True:
         score+=1
     else:
         position.pop(0)
-    
+    if x<0 or x>630 or y<0 or y>450:
+        exit()
     # 将背景图画上去
     screen.blit(background, (0, 0))
     # 将贪吃蛇的头画上去