If you just arrived in Shanghai and don’t have a friend network yet, the fastest way to find a room in a shared apartment is probably to check international websites like rental portals and online communities.
A big advantage of the apartment sharing habits in a dynamic city like Shanghai, that it is relatively casual with the goal in mind to solve the problem of finding and providing housing, instead of making it a bothersome process that might even include casting rounds organized by the current tenants in order to find the best roommate Shanghai has to offer. However, that might mean that you can get severely unlucky with your roommates. Even if the chemistry is good among current tenants, people change often, as their exchange study is coming to an end, or their employer is sending them to another office. Therefore, flat-sharing in Shanghai is not for those without a thick skin.
However, if you have a tight budget (let’s say less than 5,000 RMB per month) and you don’t want to live too far away from downtown, your choice is between living in a shoebox, or in a shared apartment.