The invention relates to a flow identification method based on posterior features. The method comprises the following steps of (1) setting posterior strategies; (2) setting derivation strategies and ageing time Tr; (3) establishing a derivation flow table; (4) establishing a backtracking data pool; (5) carrying out matching of the posterior strategies on packets; (6) extracting flow feature information contained in packets hitting the posterior strategies, establishing table items of the derivation flow table, and storing integrated flow feature information and timestamp Tm when matching occurs in the table items; (7) writing entered packets into the backtracking data pool to carry out delayed time processing, reading the delayed packets and extracting the flow feature information, retrieving the derivation flow table according to hash values of the flow feature information, recording the current time as Tn, and marking the current packet as a hitting packet if the flow feature information in the derivation flow table is matched with the flow feature information of the delayed packets and the condition that Tn-Tm