Could be anything. Most common in newer buildings or recently renovated buildings are a dual outlet with type A (US style 2 prong) on the top and the type I angled 3 prong on the bottom.
If you come without the right adaptor plug in your kit, the hotel desk will usually have something you can borrow...also, any Chinese supermarket, department store, or regular market has universal adaptors which are inexpensive to purchase.
Tip: if bringing a hair dryer from the USA, don't plug it into a hotel bathroom socket marked for 110v/shavers only. Use an outlet in the room with a converter or if a dual-voltage, set appropriately. Or use the one provided by the hotel.