Abstract: This invention is with regard to a kind of Long-acting disinfectant. Its ingredients are composed of 2,4,4′-trichloro-2′-Hydroxy diphenyl ether, amino emulsified-silica resin, 1,2 propanediol, fatty alcohol polyethenoxy ether and distilled water. First, the fatty alcohol polyethenoxy ether should be mixed with distilled water, 2,4,4′-trichloro-2′-hydroxy diphenyl ether is to be put into a high speed agitator, to make the mixture in the agitator dissolved by stirring at the temperature of 50˜70° C. When the temperature has been lowed down, the amino-silica-milk resin should be added. After stirring in the agitator at low revolution speed for several minutes, provided the mixture is homogeneous, the end product can be obtained. The long-acting disinfectant has the specific properties of excellent disinfecting effect, long-acting potency, repeated-pollution resistant, non-toxic & safe etc.