diff --git a/snake.py b/snake.py
index ea37bdb..1f513de 100644
--- a/snake.py
+++ b/snake.py
@@ -53,13 +53,17 @@ while True:
     else:
         y += 30
     position.append((x, y))
-    position.pop(0)
+
     # 将背景图画上去
     screen.blit(background, (0, 0))
     # 将贪吃蛇的头画上去
     if x == apple_x and y == apple_y:
-        apple_x = random.randint(0,660)
-        apple_y = random.randint(0,480)
+        num1 = random.randint(1,22)
+        num2 = random.randint(1,16)
+        apple_x = 30*num1-30
+        apple_y = 30*num2-30
+    else:
+        position.pop(0)
     screen.blit(snake_head, position[-1])
     
     # 将贪吃蛇的身体画上去