The air flow range is 150 m3/h~800 m3/h, applicable to sites such as homes, conference rooms, labs, offices, equipment rooms, restaurants, and gyms. The installation is convenient. The machine is installed in the ceiling, without occupying the indoor effective space or affecting the interior decoration effect. The machine can also be turned upside down for installation to improve flexibility. The noise is lower. The international popular structure design, non-metallic material and the accurate and consistent mold production ensure the perfect silent effect. More complete functions are implemented, including didirectional ventilation, air purification, energy recovery and bypass system.