The invention discloses a method for detecting isocarbophos in a NaH2PO4 buffer solution by means of chlorinated Hemin peroxide enzymatic activity catalysis colorimetric specificity. Reagents used in the method mainly include Hemin, H2O2 and 3,3',5,5'-tetramethyl benzidine (TMB). Hemin catalyzes and oxidizes TMB under the action of H2O2, so the N atom in molecules of TMB loses one electron, a system color is greatly changed from colorless to blue or blue green, and at the time, the characteristic absorption peaks of the product are 370 nm and 650 nm. After Hemin is incubated in isocarbophos for a certain period of time, the catalytic activity is enhanced, so the substrate TMB loses two electrons and becomes a diimine structure, at the time, a blue green system becomes yellow, the characteristic absorption peak occurs at 450 nm, and the change amplitude of the light absorption value at 450 nm is in direct proportion to the concentration of isocarbophos.