Abstract: This paper mainly reported the DNA damage effects of heavy metals Cd2+,Pb2+ and Zn2+ at 0.05mg/L,0.5mg/L and 5.0mg/L level and their interaction at 0.5mg/L level on hepatopancreas of loach Misgurnus anguillicaudatus by SCGEfor 1-35 days exposure.For each test group,20 loaches with similar body size (5.17-7.99g:11.79-13.21cm-were selected and kept in aquaria with dechlorinated water at 22 ±1 ℃ and fed a commercial diet every 48h.According to the percentage of damaged DNA with tail and its TL/D (tail length to diameter of nucleus-value,it probed into the relationship between DNA damage degree and heavy metal dose and exposure time.The results showed that the percentage of damaged DNA and the TL/D value was increasing with the exposure time prolonging.Of all the treated groups,5.0mg/L Zn2 + treating group had the highest percentage (84.85%-of damaged DNA at 28d exposure and the biggest TL/D value (2.50-at 35d exposure.During the first treated week, the damnification of DNA mainly revealed as the 1st level,after that time,the 3rd damaged level was mostly shown and the per2 centage of damaged DNA was beyond 80%.The joint toxicity effects among Cd2+,Pb2+ or Zn2+ manifested much complex,but it generally displayed that the existence of Cd2+ could enhance the genotoxic of Pb2+ or Zn2+.In conclusion,the results suggest that there is a significant time and dose effect relationship between the heavy metal Cd2+,Pb2+ or Zn2+ treatment and DNA damage in hepatopancreas of loach,and the SCGE could represent a useful test to evaluate the genotoxic of environmental contamination by heavy metals on aquatic organisms.