One document, from booking to the gate
The regulator's own passenger-services page lists a valid passport among the documents accepted for a domestic flight, and states that a passenger taking a domestic flight must use the same valid boarding identity document for ticketing, check-in and security. Book on your passport and everything downstream has to match it.
Source: Civil Aviation Administration of China (CAAC), passenger-services section of the CAAC portal (www.caac.gov.cn) — Air travel basics — Boarding: use a valid identity document (航空旅行常识 · 乘机 · 使用有效身份证件) (source published 16 March 2023; read August 7, 2026)