Multicast service processing method, system and access device

The invention discloses a multicast service processing method, a system and an access device which are used in a multicast service access network. The method comprises determining whether to allow a multicast channel applying to join to join a current service port when receiving a multicast channel join packet; if so, forwarding the multicast channel applying to join, and otherwise, inquiring, in the currently forwarded channel of the service port, whether a multicast channel exists which has not received any response before the timeout of the inquiring response of a particular group after applying to leave; and if so, stopping forwarding the multicast channel applying to leave and forwarding the multicast channel applying to join, and otherwise, refusing the joining of the multicast channel. Through the invention, the time delay of channel switching in an IPTV service can be reduced, and the service quality can be improved.