As well known for Korean, China government doesn't allow people to have religion, because it is socialism society. It is well know not only for Korean, but also for the other countries.
However, one strange thing is that I cannot find specific data for legal regulation for religion in China. All I have found are mostly the government protect the right for religion, and lots of people have already believed in many different religions. Especially after 'cultural revolution', China government has promulgated and encouraged many people. Answer.com
Wikipedia said all of officer in China cannot have religion, which is strange, but although close to our common sense, it is not enough. Does really China government suppress religion? BB strongly told me No.
One thing, which still makes me suspicious, is Tibet. These days they fight to be independent from China government. It seems like political problem, but it could be religious problem, Petrik told me.