The present disclosure relates to the communications field, and provides a frame synchronization method, user equipment, and a base station, to implement frame time synchronization in a high-low frequency hybrid communications system. In one example method, a user equipment completes synchronization of a first frequency frame, determines a first moment of the synchronization of the first frequency frame, obtains a receive time difference, and completes synchronization of a second frequency frame according to the receive time difference and the first moment. The receive time difference is a time difference between a moment at which the user equipment receives the second frequency frame and a moment at which the user equipment receives the first frequency frame.