diff --git a/snake.py b/snake.py
index abb69e4..67d1b2d 100644
--- a/snake.py
+++ b/snake.py
@@ -60,6 +60,8 @@ while True:
         score=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
@@ -67,7 +69,7 @@ while True:
     # 将贪吃蛇的身体画上去
     for i in range(len(position)-1):
         screen.blit(body, position[i])
-
+    
     
    
     screen.blit(food,(apple_x,apple_y))