char Timer_buf[] = "00";
char code LCD_line1[] = "jiaodu:  0  du ";
char weight_1[] = "";
改成：
char code LCD_line2[] = "Weight:   0kg ";
char Timer_buf[5];
char code LCD_line1[] = "jiaodu:  0  du ";
unsigned char weight_1[4];
没固定长度的数组系统会默认给一个长的值。显示不好控制。再加上你的W_LCD_STR()遍历了整个数组。所有才会出现后面的乱码。

修改一下45行代码如下
char code LCD_line1[] = "jiaodu: 0du ";

修改一下试看
char code LCD_line1[] = "jiaodu: 0du ";

得空看看，你用什么板子？