Discloses is a gateway, base station, communication network and synchronization method thereof. The method comprises: at time T1, sending from the gateway to the base stations a synchronization request signal; at time T2, receiving by the base stations the synchronization request signal; at time T3, sending from the base stations to the gateway the synchronization response comprising the times T2 and T3; at time T4, receiving by the gateway the synchronization response signals; and calculating for the base stations a mapping relationship between the time system of the gateway and the time system of the base station is calculated based on the times T1, T2, T3 and T4. With the configuration and method proposed in present invention, it can be avoided the problem that accurate synchronization between the gateway and the base stations can not be reached for MBMS data packets in LTE because of path delay and jitter error, so that every base station can specify the same transmitting time for MBMS data packets to guarantee that UE could implement correct RF combining.