Unfortunately there is no OW airline in Mainland China. The only possibilities are connections to various cities from Hong Kong (and possibly from Japan - there may be code share flights).

At this moment, the only OW airline with routes to China is Cathay Pacific. It only services between Hong Kong and three cities in China - Beijing, Shanghai and Xiamen. Most of the flights are at very odd hours. When Dragonair joins OW, there will be a lot more, still between HK and various Chinese cities. JAL is also joining OW but I expect that means more flights between Japan and China only.

If you choose OW, the best bet will be flying Air China or China Eastern etc., once you get into China. Please note that buying these tickets from outside China is more expensive as they will be sold at list prices. If you have friends in China, or when you get into China, you can buy the same tickets at 40%-70% discount, and most likely, they can even deliver the tickets to your hotel - there is a catch, you may need to buy about 3 days ahead.