The invention includes programs at client end, programs at SIP server end, program for selecting peer-to-peer bodies, and programs at stream media server, which are setup at client end, SIP server, expanded media server, and stream media server in sequence. Based on SIP protocol, using P2P network, client end requests program from SIP server. The SIP server forwards the request to an expanded media server. The expanded media server selects best program source, which can be other client or a stream media server. Based on address of the program source, client end can down load program of stream media, and sends information of buffering program to the expanded media server. Client end or stream media server also can send information of changing node state to the expanded media server in order to cause refreshing database of media information. Advantages are: small time delay, small bandwidth consumption, and good audio/video effect.