Sim card problem, anyone help me?

Toyo, it depends on what packages you choose. If the card is only for calls, then you won't have internet data package. But it won't be a problem. When you buy the sim card, you just tell the staff that you want to have access to the internet except making calls. Then they will provide you different packages (50m, 100m, 300m or 1g per month). Just make sure that you don't exceed the limit, otherwise the charges will be expensive.

As Linda said, it depends on the packages, also the carriers. There are 3 carrirers in China. I have used China Unicom's service, there is a plan/package table at China Unicom's offical website(in Chinese, but google translate would handle it). Moreover, for promotional purposes, carriers somtimes have promotional sim cards which are sold by participating merchants, much more cheaper than standard.