An uplink synchronization method and an apparatus are provided. The method includes: sending, by a network device, a timing advance command to a communications device, where the timing advance command includes a timing advance TA reference value, and the TA reference value corresponds to a carrier in a timing advance group TAG; determining, by the communications device, a TA offset of the carrier based on carrier information of the carrier; and adjusting, by the communications device, an uplink transmission timing of the carrier based on the TA reference value and the TA offset of the carrier.