A method for implementing multicast includes: receiving or generating an internet group management protocol IGMP packet; judging whether the packet is a first join packet or a last leave packet of a multicast group, and adding an identifier indicating whether the IGMP packet is a first join packet or a last leave packet of a multicast group to the IGMP packet, where the identifier is used for a subsequent entity not to perform multicast processing on the IGMP packet when judging that the IGMP packet is not the first join packet or the last leave packet of the multicast group according to the identifier; and forwarding the IGMP packet to the subsequent entity. Therefore, the packet processing pressure on the network apparatus is relieved, and meanwhile, the IGMP packet requirements in the practical network are met.