Agents for non-fiction books about China?

I cannot help directly, but it might be a good idea to check the publishers of similar books (and contact them If you have not already done so). May I also suggest you check publishers in the USA and Canada (even Australia and India).

Of course it all depends on what your book is about; is it technical, is it about animals, is it about the political situation? All these things will have a bearing on whom you might approach.

This may be obvious to you, but with limited information in your orginal enquiry, it is the best I can do.