Buy a Chinese SIM (China Mobile, Unicom or Telecom) at the airport, a phone shop or with help from your school. You will need your passport for registration.
A local number makes WeChat, banking and deliveries much easier. Ask for a plan with enough data for maps and messaging; campus Wi‑Fi is common, but a SIM keeps you connected on the move.
Write down your phone number and store it in your passport sleeve. If you lose the phone, go back to the shop with your passport to recover or replace the SIM.