Congestion control mechanism for multicast is one of the key problems of designing multicast protocol. In this paper, a congestion control mechanism for multicast is presented: RBMCC, which based rate and initiated by both sender and receiver. RBMCC uses three factors (loss rate of receivers, aggregated ACK of intermediate nodes and TCP-friendly rate computed by sender) to provide timely and accurate response on behalf of congestion. Experiment results show that RBMCC is scaleable and TCP-friendly.