This series of circulation fan is widely applied in the greenhouse and animal building for ventilation, especially in the closed shed with large moisture density and in the place where the air isn't easy to flow. The relay ventilation in directional arrangement method could make the mixed hot and humid air in shed flow more sufficiently, with ## cooling effect. The installation of flower gardening greenhouse could form the recirculating air flow so that the air could flow more evenly. Such product has low noise, big air volume and is soft. It is ideal ventilation cooling equipment of longitudinal and transverse circulation recirculating air flow by virtue of low power consumption, high efficiency, light weight, convenient installation and usage, etc.