Peer-to-peer (P2P) network is a novel technology that economically and efficiently delivers multimedia service to end user. According to the statistic collected in recent years, peer-to-peer, which is the most predominant application of internet family, carries over 60% internet traffic, and so a study of the peer-to-peer network performance is necessary to guarantee Quality of Services. It is a big challenge for researchers to construct a monitoring and measurement service in large-scare heterogeneous peer-to-peer network. Moreover, benefited from the rapid developments of peer-to-peer technology, peer-to-peer media streaming service base on application-layer multicast technology becomes one of most important application service in the broadband network. It is another meaningful question we should focus on to construct an economical and efficient multicast tree in peer-to-peer network with underlayer topology measurement.Research on the peer-to-peer network performance mornitoring and improvement is discussed in this thesis. Now, let's introduce it in brief as