Method and network system for multicast service transmission

The invention discloses a transmission method of multicast service, the method including: a master entity receiving multicast MBMS service data; the master entity processing the service data through a radio link control RLC layer and a media access control MAC layer, and transmitting the data block and interface transmitting time mark obtained through the MAC layer processing to auxiliary equipment of the master entity; and adding the interface transmitting time mark on the data block in the processing process so as to form a data package being transmitted to a slave entity; the slave entity transmitting the interface transmitting time mark and the data block obtained through the MAC layer processing to the auxiliary equipment of the slave entity; the auxiliary equipment of the master entity and the auxiliary equipment of the slave entity transmitting the data block through the MAC layer processing when the interface transmitting time is arrived. The application of the technical proposal provided by the invention can realize synchronous transmission of MBMS service.