This application provides a PBCH transmission method and an apparatus. The method includes: receiving, by a terminal device, a PBCH sent by a network device, where the PBCH includes seven most significant bits of an SFN of a radio frame in which the PBCH is located; determining, by the terminal device, a least significant bit of the SFN based on indication information of the least significant bit of the SFN; determining, by the terminal device based on the PBCH, a scrambling code of the PBCH, and determining two remaining bits of the SFN based on a one-to-one correspondence between the two remaining bits of the SFN and the scrambling code of the PBCH; and determining, by the terminal device, the SFN of the radio frame in which the PBCH is located.