"后来调试发现 问题出在这里 "

this example demonstrates two things:

1) what you think is wrong may not be wrong: you were adamant about the problem being in the isr when in fact it is somewhere else. it brings to question a) your approach / thought process; and b) your credibility.
2) many times, you have to help others help you. in this case, posting your complete code would have been helpful.

"这个东西无论你以什么方式置0 都会出现问题。不操作这一位就正常了。"

maybe you should look into the datasheet to see what it does and what its default (POR/Reset) values are and see if that's consistent with what you want to do.

programming is not a trial-and-error process, unless you want to remain clueless.