Abstract: A per-flow rate controller is disclosed. The controller includes a queue classifying unit, a queue memory unit and a queue selecting unit. The queue classifying unit receives a plurality of per-flows and then classifies them by the source port address of each per-flow group. The queue memory unit includes a plurality of queues. The queue memory unit stores the packets into corresponding queues according to the classifying result of the queue classifying unit. Finally, the queue selecting unit selects the queue for frame transmission and controls the output throughput rate of each queue according to user settings.