Multi-cast method and multi-cast system and multi-cast device

The invention discloses a multicast method, which includes the steps as follows: distribute intragroup keys and multicast group labels to all multicast groups; a sending end receives a multicast frame from the outside, the multicast group which the multicast frame belongs to is determined, the multicast frame is encrypted by using the intragroup key corresponding to the multicast group, and the encrypted multicast frame is sent to a receiving end; the receiving end identifies the multicast group which the multicast frame belongs to according to the multicast group labels, and decrypts the received multicast frame by using the intragroup key corresponding to the multicast group. The invention discloses a multicast system, multicast equipment, another multicast method and aother multicast equipment. The technical proposal of the invention improves the multicast security and reduces the system burden.