In this paper,a system for dectection of organophosphorus(OPs) pesticides by plant-esterase as the inhibitive enzyme was studied.The condition of detection was optimized by the Uniform-Design Method,and the factors which may interfere with the esterase activity were analyzed.The inhibition effects of seven kinds of OPs to esterase were compared.The method for the detection of OPs was established and applied to vegetable samples successfully.