dear developers of Texstudios,
I encountered this problem all of a sudden and can't recover since then.

you can see the bracket if totally abnormal. How to solve this? Do I press some keys that caused this problem?
Ps: I have already reinstalled texstudio, problem remains.
have you tried a different font for text ? maybe one which is monospaced ?
I posted this answer. Thank you very much ! You saved my day, change a font really works
Just out of curiosity, which font does produce the problem?
I forgot the name of the original font that cause the problem, but as tested Lucida Sans Typewriter can cause the problem
can you post the offending text in a file ?
Putting chinese charcters is a little arbitrary for Europeans ...
I share the tex file http://s000.tinyupload.com/?file_id=72127807392659467708
Works here with the given document and Lucida Sans Typewriter. Therefore, the problem seems to be even more specific, maybe a certain version of that font?
Anyway, since changing to a different font solves the issue, I don't think investiigating further is worth it.