The invention provides a Fenton and Fenton-like system fortifier and a using method thereof, which relate to a water treating fortifier and a using method thereof and overcomes the defects that the watter treatment reaction speed is low because of Fenton systematic reducing agent. The fortifier is selected from hydroxylamine, hydroxyl-ammonium perchlorate, hydroxylamine sulfate, hydrazine, N,N-diethylhydroxylamine, carbohydrazide, ethanolamine, a hydroxylamine solution and N,N,N',N'-tetra substituted phenylenediamines. The using method has the following steps of: adding the Fenton and Fenton-like system fortifier, fortificated chemicals and peroxide into the treated water body; and then, uniformly stirring to react. The fortifier can accelerate the reaction of water treatment and decrease the using amount of the fortificated chemicals.