Abstract: It has been more important to accurately classify and identify various applications in network flow nowadays. Aiming at the disadvantages of current analysis on flow and integrated with relevant research accomplishments, the paper proposed that network flow analysis could be conducted with fine-grained Packet-Level sequence property, based on the bi-directional dynamic network flow model. The relationship between sequence properties and network flow patterns was established to create an efficient network flow classification method that has nothing to do with port.