In order to solve the problem of constrained resource and insufficient calculation ability in airbased backbone network and the problem of not fully considering load balancing and difference in requirement of QoS(quality of service) guarantee in the traditional SOAR(simple opportunistic adaptive routing) algorithm, a new algorithm was proposed to support the QoS named improvedSOAR routing algorithm. The algorithm defined comprehensive expected transmission count to describe the comprehensive state of links on the basis of taking the link congestion control and load balancing into consideration. It can effectively reduce the probability of network congestion. A route selection strategy was designed for QoS based on AHP method, according to the service type difference in transmission network. It can achieve the dynamic matching between the path selection and the different service type. Simulation results show that the improved-SOAR routing algorithm has better performance in the transmission delay, the throughput and the throughput rate than the traditional SOAR routing algorithm under heavy network load. When there are different types of services in the network, the improvedSOAR routing algorithm adaptively selects the best transmission path according to the difference of requirement about the QoS guarantee.