"The following items may be imported into China by passengers staying less than 6 months without incurring customs duty:
400 cigarettes (600 cigarettes for stays of over six months); two bottles (up to 75cl) of alcoholic beverages (four bottles for stays of over six months); a reasonable amount of perfume for personal use.



Chinese customs authorities may enforce strict regulations concerning temporary importation into or export from China of items such as antiquities, banned publications, some religious literature, or vehicles not conforming to Chinese standards. It is advisable to contact the Embassy of China in Washington or one of China's consulates in the United States for specific information regarding customs requirements."

no idea if there is an official banned list, but common sense should prevail.

no raw fruits, vegetables, meats
no drugs
limited amounts of booze
if you bring multiples of the same electronic items (e.g. ipads) you could be asked to pay a fine. suggestion - carry one, pack one.

long life milk and cereals are fine to bring in, but if you're going a major city you can pick them up in any store. I can buy organic new zeland milk at carefour or President cheese, etc. Cereals are also pretty common through pricey at time.