The invention discloses a stream aging method and network device. The method comprises steps of: establishing a forward directional stream table, a reverse directional stream table and a session table, wherein the forward and reverse directional stream tables comprise identifier information and a session table index of the stream, the session table comprises accelerating transmitting information of the forward and reverse directional streams; receiving the forward and reverse directional stream packages, searching the forward and reverse directional stream tables according to the identifier in the package; searching the session table according to the session table index in the stream table; transmitting the package according to the accelerating transmitting information in the session table; when the session table hit exceeds, deleting the session table and corresponding forward and reverse directional stream tables. The invention relates the forward and reverse directional stream tables with unified session tables. Stream aging depends on aging of the session tables, which avoids session early termination caused by unilateral stream termination and saves resources.