By analyzing packets of the transport layer and the traffic flow statistic characteristics in the peer-to-peer (P2P) applications, a new P2P traffic identification system is presented. The new method in the system relies on the observation of the first few data packets of a TCP/UDP connection. It not only can identify more P2P applications, but also can identify the known and unknown P2P applications even if the data of them is encrypted. According to the results by passing a large number of tests, the system has higher identify-rate to identify the P2P applications and lower false negative and false positive. It has good effects in the actual network.