well , while dealing with chinese characters - there are MANY problems that can cause this , but many times , it is as simple as the encoding of the php files. (simple as a figure of speech - you will soon understand why )
A PHP file is a TXt file . and even if it is only a what seems a "simple" txt file, it can actually be encoded in many ways .
ANSI,Unicode ,UTF-8,UCS-2 Big Endian , UCS-2 little Endian, etc, etc ...
..and all of which can be with BOM or without BOM. :-)
Now, Chinese has their own character encoding method, which are even more complicated and highly confusing. some of the ones I know are :
BIG5, GB 2312, GBK, HZ , and so on and so on ...
further more - to you they might look the same , but for a Chinese person they are different . they are divided into categories (mainly 2 - Chinese traditional and simplified) AND each is used in different geographical regions . (for example, Chinese traditional is Taiwan, Hong Kong, while simplified is in mostly . mainland china)
so.. after this introduction, what you have to do , is actually open all your files in a software that can read the character encoding , change it , and try o see if it works .
I recommend notepad++ . go to FORMAT menu, change the encoding, see if the characters are still what it should be , and if it is - save, and then try again.
In my experiance , the best format for almost all foreign languages is actually UTF-8 without BOM.
that being said - it is always a bad practice to use foreign characters (especially chinese) for URLs. in extreme cases your server might even not be able to handle them .