Never been to China, but I don't think the stock Xbox 360 power supplies can handle 220V (should list voltage range on power brick). In this case, you'll need a 220V, 200W (minimum) AC/DC power supply. Like this one
Only problem is that I'm not sure if the one in the link above comes with the right wall plug for Shanghai. I've heard that they use the same as Australia, which would be this
If you get both, you should be covered. However, I would imagine you could get both, and especially the wall cable, in Shanghai, but I have no idea where.