Abstract: A simple and rapid method was developed to detect 23 kinds of organophosphorus or carbamates pesticides which were illegally added in 9 kinds of different pesticide formulations and 1 kind of leaf fertilizer. The pesticide formulations or leaf fertilizer were diluted with phosphate buffered saline solution and the supernatant was transferred into another test tube where the cholinesterase and chromogenic reagent were added orderly. This mixture was stirred and reacted for 5 min. The final detection was performed by a pesticide residue rapid measuring instrument which is used to measure the absorbance change of the mixture during 0-3 min at the wavelength of 412 nm after the substrate was added. Additionally, the limits of detection of omethoate, phorate and methyl parathion in 9 kinds of different pesticide formulations and 1 kind of leaf fertilizers were verified. It was concluded that the limits of determination were ranged from 0.03 mg/L to 4.4 mg/L. The inhibition rates are 50%(56%-100%) when the application levels in 9 kinds of different pesticide formulations and 1 kind of leaf fertilizer are close to or marginally higher than the limit of detection. In conclusion, the hidden compositions mentioned above which are illegally added in pesticide formulations or leaf fertilizer could be qualitatively determined by the present method.