A multicast-supported virtual local area network switching system and a method thereof comprise a switching engine, a CPU unit, further comprising a mapping storage unit for storing the mapping relationship of the virtual local area network and the multicast stream pushed to the switching system by it, and a switching table storage unit for storing the corresponding relation between ingress virtual local area network and egress virtual local area network; the switching engine receives the internet group management protocol message from the user virtual local area network and transmits the message to the CPU unit for processing, if it is Internet group management protocol join/leave message, the CPU unit looks up the mapping storage unit and forwards it in the looked-up multicast virtual local area network; the switching engine receives the Internet group management protocol messages or multicast data frames from the multicast virtual local area network and forwards them in the looked-up user virtual local area network by looking up the switching table storage unit.