Multicast is generally referred to transmissions from one source to many destinations or many sources to many destinations. Security in multicasting is one of the key issues that has to be considered, so for data transmission to be secure in multicasting, key management has to be considered. When, any one of the group member join or leave from multicast group, at that time, rekeying is necessary. Huffman Tree Algorithm which can't works dynamically, for adaptive use of Huffman tree structure, rekeying for multicast group can be done easily. For that, the Huffman key structure which represents the keys can be adjusted in accordance with the probability or frequency of multicast group members or individual members entering in or out from multicast group, as the frequency here denotes the probability that a member may join in or leave from group in coming future. In this paper, Huffman tree scheme that we proposed can provide the security for rekeying of multicast group, and moreover we can provide the average rekeying cost which is minimum even while adjusting Huffman key tree structure. © 2012 IEEE.