Abstract: To evaluate the effect of 17-estradiol on the antioxidative enzymes in larvae of Perinereis aibuhitensis,we exposed the worms to 17-estradiol at different concentrations (0.1 gL-1, 1 gL-1, 10 gL-1, 100 gL-1 and 1 000 gL-1), and measured the superoxide dismutase (SOD)，catalase (CAT) and glutathione S-transferase (GST) activities on 2nd, 4th, 6th and 8th day, respectively. The results show that SOD, CAT and GST activities in 10 gL-1 treatment group increased significantly, and SOD and GST activities decreased notably in 1 000 gL-1 treatment group on 2nd day. SOD and GST activities were induced at different degrees in every treatment group on 4th day. CAT and SOD activities were suppressed in lower-concentration groups (0.1 gL-1 and 1 gL-1) on 6th day and in higher-concentration groups (100 gL-1 and 1 000 gL-1 ) on 6th day, respectively（P0.05）. CAT activity was induced at different degrees in all groups except 1 000 gL-1 group (P0.05); GST activity was suppressed in 10 gL-1group; SOD activity was also suppressed in 17-estradiol treatment groups on 8th day. It is indicated that SOD, CAT and GST activities in P.aibuhitensis were induced by exogenous 17 -estradiol, and the extent was related with the exposure concentration and time.