The invention discloses a QoS control method of distinguishing service priorities in a SDN, the method comprises the following steps: firstly, performing service priority division for data services inthe SDN according to QoS needed for the data services, then, in distinguishing routing, taking link congestion measurement as link cost criteria for a service data stream with the highest priority, and taking time delay needed for the service data stream with the highest priority as a constrain condition, routing through a Lagrange Relaxation aggregation criteria algorithm, and for the other service data streams, routing through a shortest path algorithm using hops as criteria; and in distinguishing queue scheduling, performing differentiated queue scheduling based on service priorities. Themethod provided by the invention guarantees end-to-end time delay of the service with the highest priority as much as possible, also guarantees different QoS of other services with different priorities in a distinguished mode, and meanwhile, the method routes the service with the highest priority to a low-congestion path, thus, utilization rate of network bandwidth and throughput capacity of network data transmission are improved.