Abstract: In order to control the communication relation actively in secure multicast, an approach is proposed, which distributes warrant containing secret key. Users get warrant in order to communicate in some multicast group. The group controller can update the users' warrants to change the users' communicate relation. This approach also uses an encryption algorithms and types' mapping table to increase the security. The result shows that this approach can set several smaller secure groups in a multicast group and change the users' communication relation actively, so as to act against attack or control the communication relation.