A communication method and an apparatus relate to fields such as V2X, intelligent connected vehicles, intelligent driving, and assisted driving, to resolve a technical problem that a current SL lacks an indication of an SL TCI identifier. The SL TCI identifier is able to be implemented in at least two ways. An explicit indication is able to be used. A first terminal apparatus sends first indication information to a second terminal apparatus. The second terminal apparatus determines the SL TCI identifier of the first reference signal based on the first indication information. Alternatively, a first terminal apparatus generates a first signal based on an SL TCI identifier of the first signal, and sends the first signal to a second terminal apparatus. Then, the second terminal apparatus determines the SL TCI identifier of the first signal based on the first signal.