Toxicity of thirteen insecticides to Propylaea japonica (Thunberg) was evaluated n laboratory P. japonicawas themost susceptible to synthetic pyrethroid insecticides andmethomyl, themost tolerant to endosulfan Toxicity ofmethomyl, fenvalerate, cyhabthrin and deltam ethrin to the P. japonica was 34 6, 223, 244 and 282 times that of endosulfan respectively. Susceptibility of the P. japonica to organophosphorus insecticides such as omethoate, sulprofos, monocrotophos was lower than to synthetic pyrethroid insecticides and methomyl, Toxicity of organophosphorus insecticides was 1.7～6.9 times that of endosulfan. Comparison between P. japonica population at Taian where insecticides application levelwas bw, and the population at Xiajin where insecticides application level was high showed 23.7-fold resistance to cyhabthrin and deltam ethrin.