Embodiments of the present disclosure provide a downlink synchronization method, an apparatus, and a system, and relate to the communications field, so as to reduce downlink synchronization complexity and improve downlink synchronization efficiency. According to the downlink synchronization method, abase station sends downlink synchronization reference information to UE by using dedicated signaling or a system message, where the downlink synchronization reference information is used to instruct the UE to perform downlink synchronization in a second cell by referring to a downlink synchronization channel of a first cell; and the base station sends, in the second cell according to location information of the UE, a beam including a downlink synchronization channel to the UE, where the first cell and the second cell include an overlapped coverage area. The embodiments of the present disclosure are applied to synchronization channel sending.