A payload-analysis approach to identification and measurement of peer-to-peer (P2P) network services is proposed. The proposed approach effectively and efficiently identifies the complicated traffic caused by P2P network services. The feature extraction, payload analysis and dynamic measurement are the three pillars of the proposed approach. The dynamics of BT connections are featured to generalize the packetcapture criteria. Followed up, a payload analysis of captured packets is used to identify and measure the traffic. The implementation of the proposed scheme has been realized on a Pentium-III computer. The results shows the effectiveness of the proposed scheme and the efficient measurement of the traffic parameters, such as peer IPs, port numbers, data rates, etc. The parameter measurement facilitates this possible bandwidth management of P2P traffic in the near future.