Abstract: In order to rapidly determine the organophosphorus pesticide residue in vegetables,esterases are extracted from four types of wheat,i.e.Jing No.9428,Jing No.9583,JingDong No.8 and Jing No.2.The inhibition rates of the esterase activity under different concentrations of parathion are compared by the colorimetric measurement.The results indicate that the inhibiting sensitivities to parathion of esterase extracted from different wheat are not the same.The esterase from the wheat of Jing No.2 is more sensitive to parathion than that from others,with detection limit of 3.0×10^-7 mg/L.Simultaneously,the temperature,time and pH of the enzymic reactions are optimized.Organophosphorus pesticide residues in vegetables are determined by the proposed method.