Key management is an important part of secure multicast. Among the representative solutions to the multicast key management, the de-centralized scheme inherits the merits of others. In this paper, we present a scalable de-centralized multicast key management scheme, introduce the main idea and analyze its advantages and disadvantages. We construct a core tree in the group member at first, whose nodes sharing a DEK and then constituting one key management level. The core node and other members in the same region form another key management level. When the member in the subgroup changes, only local sub-tree re-key. If the member in the core tree changes, the DEK of the core tree is updated. Thus the overhead of re-key decreases. When data are transmitted between different subgroups, the nodes in the core tree decrypt/encrypt data only once before switch it to local subgroup members, thus the cost of data transmission is decreased. When the size of group becomes large, we use batch re-key scheme to alleviate the cost of rekey further. The scheme has highly robustness, good scalability and lower cost.