With the proliferation of the high speed, broadband network technologies, the peer-to-peer (P2P) live multimedia streaming becomes more and more popular. In this paper, we proposed a SIP-based P2P multicast scheme for live multimedia streaming. By utilizing the SIP protocol, our proposed scheme not only minimizes the initial delay for playing live media streams but also reduces the infrastructure deployment cost. In addition, we proposed a passive mechanism to construct a balanced multicast tree without a centralized server to maintain the topology of the P2P overlay. The performance evaluation shows that our proposed scheme can minimize the initial delay and constructs a balanced multicast tree for live multimedia streaming successfully.