Thanks for your help.

You give me a clue to deal with this problem!

I immediately found this http://support.mozilla.com/zh-TW/questions/800955#answer-155...

And carefully checked all of my extensions. I found a Z extension hide itself in FF extensions list. Finally I deleted it.

I think this is a good way if FF can give users some clue to deal with crash problem. It might be a great help. Thank you.