The law that mandates all foreigners to register their residence within 24hours of arrival in China at a police station.(If you stay in hotels, then you’re fine. The government requires hotels to register their foreign guests as part of the check-in process.)

Shanghai launched a self-service resident registration system to help streamline this process. Now all foreign tourists and expats staying in Shanghai can simply declare their information and place of residence online. 

You can access the self-service registration website by clicking on this link: https://crjzndg.gaj.sh.gov.cn/24hr

Old rules still apply

Expats with residence permits only need to register whenever they renew their residence permits(or move to a new address). Others would still need to register each time they enter the country. Others include tourist visas, business visas, and family visas.