Abstract: This study combined micronucleus test (MN) and single cell gel electrophoresis technique to assess the genotoxicity of imidacloprid and avermectins to Pardosa astrigera Koch. The micronucleus assay is already widely used in genetictoxicity evaluation due to its clear endpoint, high reproducibility and easy accessibility. The single cell gel electrophoresis technique (comet assay) is a simple, sensitive, reliable, and rapid method to detect DNA damage in eukaryotic cells. P. astrigera, one of the main natural enemies of destructive insects for cropland, orchard, vegetable fields and forest ecosystems, widely distributed in most areas of South and North China. The objective of the study was to achieve a more comprehensive understanding of the effects and potential risks on the spiders of imidacloprid and avermectins, which are normal pesticides, used in the agricultural and forest ecosystems. The results showed significant differences ((P < 0.05, or (P < 0.01) in micronuclei frequency of P. astrigera hemocytes between imidacloprid and avermectins treatments and the control. The micronuclei frequency increased with concentrations of the two pesticides, showing evident dose-effect relationship. The correlation coefficients of imidacloprid and avermectins concentrations with micronuclei frequency of hemocytes were 0.672 8 and 0.989 9 for cephalothorax, 0.800 6 and 0.985 8 for abdomen of P. astrigera respectively. The comet assay showed that DNA damage percentage of pesticide-treated P. astrigera was significantly different from that of the control ((P < 0.01). DNA damage scores expressed as arbitrary units (AU) increased with two pesticides concentrations showing dose-effect relationships. The correlation coefficients of DNA damage in cephalothorax and abdomen hemocytes of P. astrigera with imidacloprid concentration were 0.948 2 and 0.970 4 respectively, and with avermectins were 0.978 1 and 0.975 6, respectively. The frequencies of micronuclei and DNA damage of the abdomen hemocytes of P. astrigera was more serious than those of cephalothorax. MN test and single cell gel electrophoresis assay in this study provided valuable information for evaluation of the pesticides risks to natural enemies and agricultural ecosystems.