Embodiments of this application provide an authentication method, device, and system, to resolve problems of wastage of performance and memory resources that may be caused by remaining n−1 unused authentication vectors (AVs). The method includes: receiving, by an authentication entity, n first authentication vectors from a unified data management entity, where n is a positive integer; generating, by the authentication entity, n second authentication vectors based on the n first authentication vectors; sending, by the authentication entity, one of the n second authentication vectors to a security anchor function entity; receiving, by the authentication entity, an authentication confirmation request from the security anchor function entity, and performing authentication confirmation on the terminal according to the authentication confirmation request; and sending, by the authentication entity, the other n−1 unused second authentication vectors in the n second authentication vectors to the security anchor function entity when the authentication confirmation succeeds.