Abstract: In order to establish a sensitive and rapid assay to test the genotoxicity of environmental genotoxin on human target cells,the authors carried out a study on the optimal duration and temperature of exposure treatment and two testing protocols for crosslinks.Results show that after exposed to 7.5 μmol/L of formaldehyde at 37 ℃ for 30 and 60 min,DNA was damaged more acutely than that for 15 min.After exposet to 7.5 μmol/L of formaldehyde at 4,23 and 37 ℃ for 30 min,DNA damage happened in all of the three groups,but at 37 ℃ DNA strands broke most.On the two testing protocols for crosslinks,increasing the duration of electrophoresis is more reasonable for the detecting of DNA breakage and crosslinks.