As the process of proliferation of the Internet progresses and multicast applications are deployed for mainstream use, the need to IP multicasting technology will become critical. Now, the research of multicast technology has become a fresh new thriving academic field. Many main results converge to such fields as the multicast routing, the flow control, the congestion control and reliable multicast. But the results referred to multicast security are very few (especially in the field of group key management).In this paper,the problems of group key management and access control for large dynamic multicast groups have been researched.A scheme based on subgroup secure controllers are proposed which solves many problems of the Iolus System and the solution of WGL, and at the same time,which simplifies the scheme of access control and meets our design aims and requirements.