The invention belongs to the technical field of a household electrical appliance product and particularly relates to an air purifier for purifying air. The air purifier comprises a front cover and a rear cover, wherein a containing space is formed by the front cover and the rear cover; the containing space is internally provided with a direct-current fan, an electronic control board, a power supply, a main board, a PCB (Printed Circuit Board) panel, a voltage multiplier and an insertion piece, wherein the voltage multiplier, the direct-current fan, the power supply, the insertion piece and the main board are arranged on the inner surface of the rear cover; the electronic control board is arranged in front of the direct-current fan; a filter is arranged on the outer surface of the rear cover; the front cover is provided with a knob switch and an air outlet; and an air inlet is formed in the position of the rear cover and relative to the position of the direct-current fan. Compared with the prior art, the air purifier disclosed by the invention not only can kill harmful bacteria, moulds and funguses in indoor air, but also can effectively eliminate awful smell dispersed by tobaccos, lampblack and garbage, and dispersed in the cooking process; and the air purifier eliminates odors dispersed by indoor ammonia, carbon monoxide, marsh gas and dispersed from a sewer exhaust pipe, can eliminate an allergic reaction of people to pollen and can also effectively kill acarids.