In order to solve the problem in deflection control of deflection algorithm,a deflection routing algorithm based on priority and burst loss threshold in OBS networks is proposed.It drops some high priority deflected bursts to provide QoS for low priority nondeflected bursts.When competition occurs,in order to protect high priority burst,low priority bursts are segmented and deflected.Then,the node uses threshold check function to decide whether to drop or to preempt the resource of low priority nondeflected bursts on deflected route.Simulation results show that although the proposed algorithm increase a little delay,it can efficiently prevent deflected burst from contending with nondeflected burst on deflected route,and reduce packet loss probability of entire networks and protect the integrity of some high priority bursts.As a result,the scheme can efficiently improve the performance of OBS networks.