SWF series mixed-flow fan is a new type fan between axial flow fan and centrifugal fan, which has advantages of both axial flow and centrifugal fan. The total pressure of mixed-flow fan is higher than the same-sized axial flow fan, and the air flow is bigger than the same-sized centrifugal fan. This series fan has advantages of high efficiency, wide and effective operation area which is widely used in ventilation system for office building, hotels and other big buildings. It can also be used in ventilation and air exchange for refrigeration house, textile plants to replace low pressure centrifugal fans or high pressure axial-flow fans.