Abstract: Two populations of Plutella xylostella were collected from Taian of Shangdong province (TA Population) and Hangzhou of Zhejiang province (HZ Population). The toxicity of 14 insecticides to the two populations were tested by dipping method in laboratory. The results showed that the resistance ratios of TA Population and HZ Population to deltamethrin were 63.9 and 52.5 folds, to chlorfluazuron were 35.0 and 122.1 folds, respectively. The toxicity of abamectin and fipronil were higher, but that of the tested organophosphorus insecticides and methomyl, etc. to the populations were lower.