Abstract: To study and evaluate genotoxicity of H2O2 and formaldehyde in the spider, pardosa astrigera, the adult of female and male spiders were treated with H2O2 at concentrations of 50,75,100,125,150µM and formaldehyde at 10,25,40,55,70µM, respectively. DNA damage of hemocytes was detected by the comet assay. CASP software was used to analyze the comet pictures. The results show that the percentage of comet, the percentage of tail length, and the tail moment of the H2O2 tested groups were significantly different from those of the control group (P<0.05). A statistically significant dose-dependent increase in DNA damage was observed. Formaldehyde induces DNA strand breaks at 10µM, but crosslinks at 25,40,55µM, and apoptosises at 70µM in hemocytes cells of spiders.