diff --git a/snake.py b/snake.py
index 27e9fd5..d1fd113 100644
--- a/snake.py
+++ b/snake.py
@@ -67,6 +67,9 @@ while True:
         position.pop(0)
     # 将背景图画上去
     screen.blit(background, (0, 0))
+    if x<0 or x>630 or y<0 or y>450:
+        exit()
+
     # 将贪吃蛇的头画上去
     screen.blit(snake_head, position[-1])
     # 将贪吃蛇的身体画上去