The invention is an air filter, which arranges a wind inlet and a outlet, there arranges a fan driven by motor in the wind channel between the inlet and the outlet, an air filter film with thickness thicker than 1mm in the wind channel, the structure of the film is bag type or box type, in which the carrier containing air filter compound is filled. The composition of the compound is: equal quantity of component A and component B and proper quantity of carrier, A is made up of FeSO4, FeCl2, L-ascorbic acid, and water; the component B is made up of ZnCl2, FeCl2, CaCl2, AlCl3, MgCl2, KCL and water. The confected A and component B are absorbed onto the carrier respectively when in use, it can be used after being dried.