A novel strategy for scheduling input packets queueing in three buffers with different quality of service constraints has been developed to improve the traffic QoS. By theoretical and simulation analysis, analytical formulas of the average circular time, retu time, queue length and delay have been obtained and the impacts of k2, p2 on the average circular time, retu time and delay have been investigated. It shows that the new schedule strategy can satisfy the QoS requirement by carefully selecting ki or pi with the arrival and departure rate of the packets being given.