An identifier update method includes: in the process of a first terminal sending data carrying a first identifier to a second terminal, the first terminal acquiring a second identifier, wherein the second identifier is used for updating the first identifier, and both the first identifier and the second identifier are used for identifying the first terminal; and the first terminal sending indication information to the second terminal, wherein the indication information is used for indicating that the second identifier carried in data subsequently sent by the first terminal to the second terminal is an update of the first identifier.