Abstract: To study the variation trends of superoxide dismutase (SOD) activity, malondialdehyde (MDA) level and glutathione (GSH) content in tissues of mantle and visceral mass of Perna viridis, we performed an experiment under semi-static conditions by exposing the samples to BDE3 (1 μg · L^-1, 10 μg · L^-1 and 100 μg · L^-1) for 1 d, 3 d, 7 d and 15 d then releasing them by clean seawater for 3 d and 7 d. The results show that during the exposing period, SOD activities of the 2 tissues in 1 μg · L^-1 group were induced very significantly (P < 0.01), and the induction rate decreased with exposing time; SOD activities of mantle in groups of 10 μg · L^-1 and 100 μg · L^-1 were more sensible than those of visceral mass. MDA level increased at first then inhibited later in mantle, while induction and inhibition alternated in visceral mass; for 1 μg · L^-1 group, the highest induction rate reached 26.04% on 3^rd day of exposing while the highest inhibitory rate reached 14.92% on 7^th day. GSH content in mantle in 1 μg · L^-1 group was induced significantly (P < 0.01) all the time, while it increased at first then inhibited later for groups of 10 μg · L^-1 and 100 μg · L^-1; in visceral mass, GSH content in 100 μg · L^-1 group was induced significantly (P < 0.01) on 1^st day, while that in 1 μg · L^-1 group increased significantly with exposing time (P < 0.01);groups of 10 μg · L^-1 and 100 μg · L^-1 showed irregular trends of induction-inhibition. After the releasing period, only individual groups recovered to the same level in the control.