This paper presents application layer multicast system of the context-aware dynamic role, which need to real time tinker up the permissions owned by consumer based on the context information. We analyse key problems of layer multicast system in application layer multicast communication. In order to solve the problems, we provide the dynamic management of members' role and permission in application layer multicast, context-aware dynamic role based access control model is presented to solve the problem. The model is analyzed based on the definitions of user assignment and permission assignment matrix. The user and resource context are collected by U-agents and P-agents. With the information collected, the users' role and permission assignments are dynamically adapted. Finally, the dynamic role based access control model for application layer multicast is implemented, which solve the key problems and which meets our demand for safety of reality and provides a strong guarantee for the safe to us.