Want to play Pokemon GO in China? You'd better give up.
Pokemon GO requires the use of Google's servers and resources for the majority of the game. Google just so happens to be banned in China because political reasons.
Now, in theory, you could set up a VPN to the States or any non-censoring country. From there, you can access Google's servers, and therefore the game. Note that setting up a VPN is not in the scope of this site, so it's left as an exercise to the reader.
Additionally, Niantic will block the game from loading anything in "unsupported" countries at this time. Meaning, if you have a VPN set up and guaranteed working, Niantic may just not be spawning any Pokemon in your vicinity because there's supposed to be nobody there to catch them.