Abstract: The antioxidant physiological responses to cadmium stress,including the contents of malondialaehyde(MDA),superoxide anion(O2·-),peroxide enzyme(POD),catalase(CAT),and the root system activity of Aegiceras corniculatum seedlings were investigated in water-culture condition.The results showed that,under the applications of Cd2+ in the range of 0.25-10 mg·L-1,the activity of root system decreased with increased Cd2+ concentration,while the content of O2·-,MDA,and the activities of POD and CAT increased.It revealed that the membrane-lipid peroxidation brought about by the superoxide anions was the main cause of the Cd2+ damage to Aegiceras corniculatum seedling.On the other hand,the protective enzymes exerted Cd2+ stress resistance at the Cd2+ concentrations from 0.25-10 mg·L-1.It indicated that increasing POD and CAT activities of the seedlings should be considered an important part of peroxidation resistance mechanism of the plant to cadmium pollution.And,the enzymatic activities might be a useful biological indicator of Cd2+ contamination.