Sim Card with data plan in China? [duplicate]

In theory a China Mobile SIM card should be able to provide 3G services. In practice I have not been able to get my (3G only) HTC phone to access the internet via such a card. China Unicomm seems to be a better offering in the 3G field. While China Mobile supposedly provides both 2G and 3G services, in practice it is a 2G service.

Buying a SIM may be best done at a big telecomms store, rather than the airport - you are more likely to get a solution that actually works. A purchased SIM does seem to be the way to go. Be aware that if you do buy any SIM in China you will be subject to the constraints of the Chinese Firewall, so although you can access data, you will not be able to access Facebook, Blogger, or (sometimes) GMail, and other services.

I had no problem getting a sim card at Unicom. I had to pay for a month though, which was 26 Yuan. That got me text, talk, and 600MB of data for a month.

I bought a SIM card from a street vendor stall. It's difficult for non-nationals to register a SIM card which must be done prior to using one. For foreigners, the vendor would typically register it himself and sell to you with a somewhat higher mark up. You need to make sure that the SIM card is registered and test it on your phone before walking away. After you've bought it, get ready for a lot of spam. Fortunately, you probably won't understand any of it...

The other answers are a bit outdated so I share the latest information. You can purchase in airports a 4G/LTE SIM card, not 3G. Either China Mobile or China Unicom is considered better than China Telecom.

However, the price might be a bit expensive in the airport; I have purchased it only at Shanghai Pudong International Airport but Beijing's would be likely similar.

Alternatively you can purchase it in the city, but it might not be a good option if you don't understand Chinese language. I recommend to buy it in the airport if you want to ensure that you have a mobile connection.

As to the free Wi-Fi, many of them require an SMS verification and it mostly only accepts Chinese phone number. Wi-Fi at most privately owned cafes and restaurants don't have this troublesome steps (but don't go to Starbucks; it requires a phone verification).