Foreigners must register before entering China.

If you are staying in a hotel, guest house or hostel, the staff will check your passport and do the registration for you. If you are staying in a private residence you are required to register your abode with the local police within 24 (city) to 72 (countryside) hours of arrival.

The police will ask for

1. A copy of the photograph of your current passport
2. A copy of your visa
3. A copy of your immigration entry stamp
4. A photograph of you
5. A copy of the tenancy agreement or other document concerning the place you are staying in. That agreement might not be in your name but it will still be asked for.