A tracking area (TA) update method, a broadcast message transmission method, and a communications apparatus, where the tracking area update method includes: receiving a broadcast message periodically sent by a satellite device, where the broadcast message alternately carries tracking area codes (TACs) corresponding to one or more TAs of at least two TAs, and where coverage of a beam of the satellite device belongs to the at least two TAs; when detecting for the first time that a TA corresponding to a TAC in a broadcast message received in a current period does not belong to a first TA list, recording the TA in a second TA list; continuing detecting a subsequent broadcast message; and determining, based on a TAC in the subsequent broadcast message, whether to initiate a TA update procedure.