The method includes following steps: in the circuit domain carried by IP of 3G communication system, adds a bearer control layer composed of bearer network control servers between the call control layer and IP bearer layer; through bearer control servers, configures the network topology of IP bearer network, and detects the resource variation in IP bearer network in real time, and selects routing strategy for traffic flow in 3G circuit domain to meet the QoS requirement, and sends down the routing strategy to the edge router in IP bearer network; the edge router labels the priority and dispatches the queue for the traffic flow matching the routing strategy, and in term of the routing strategy, makes priority forwarding for the traffic flow to guarantee the QoS of the traffic flow. |