Fresh air fan

The utility model relates to a fresh air fan. An air outlet and a first indoor air inlet are formed in one end of a case in the vertical direction; an outdoor air inlet and a second indoor air inlet are formed in the other end of the case; indoor air outlets are respectively formed in a side of the outdoor air inlet and a side of the second indoor air inlet; a filtering mechanism, a total heat exchanger, an HEPA (high-efficiency particulate air) filtering net assembly and a fresh air motor are sequentially arranged from the outdoor air inlets to the air outlet; the trend of fresh air of the fresh air fan can be determined according to actual indoor environment assessment; the total heat recovery efficiency is above 80%; sensible heat and latent heat can be exchanged; a real-time monitoring effect can be achieved through a sensing mechanism; and discharged fresh air can be filtered through the filtering mechanism and the HEPA filtering net assembly. By the fresh air fan, wiring conduits are flexible, the fresh air which is in an optimal state can be delivered to an indoor environment, and the relation between fresh air replacement and energy consumption can be considered. The fresh air fan can meet using demands of most of users and is environment-friendly and energy-saving; and by the fresh air fan, indoor air can make people comfortable.