A reference time determining method and apparatus are provided, to prevent aberrations in a control instruction execution time caused by inconsistency between a reference time of a terminal and a reference time of a control device in the conventional technology. In this application, the terminal may receive a plurality of pieces of time reference information sent by the network device. When the terminal receives indication information from the network device, the terminal may select, based on the indication information, one piece of time reference information from the plurality of pieces of time reference information as first time reference information. The indication information indicates the first time reference information. After determining the first time reference information, the terminal may determine the reference time of the terminal based on the first time reference information.