The effects of different concentrations of sodium selenite（1,3,6,12 mg/L） on the AsA-GSH circulatory metabolizing enzyme activity,glutathione metabolizing enzyme activity,the contents of AsA and GSH,the redox state of ascorbic acid and glutathione,chlorophyll and fresh biomass per plant of maize seedlings under cadmium（Cd） stress were studied. The results showed that Cd stress significantly reduced the activities of γ-GCS,GST,DHAR and APX,the contents of AsA and GSH,the ratio of GSH/GSSG and AsA/DHA,chlorophyll content and fresh biomass per plant of maize seedlings,compared with the control. However,Cd stress increased the activities of GR and MDHAR,as well as the contents of MDA and H₂O₂ of maize seedlings. Compared with Cd stress alone,the addition of sodium selenite at different concentrations significantly increased the activities of DHAR,MDHAR,APX,GPX and GST,the contents of AsA and GSH,the ratio of GSH/GSSG and AsA/DHA,chlorophyll content and fresh biomass per plant,but significantly reduced the contents of MDA and H₂O₂. Except 12 mg/L sodium selenite had no significant effect on GR and γ-GCS activities,other concentrations of sodium selenite all significantly enhanced the activities of GR and γ-GCS. Among all the concentrations of sodium selenite,3 mg/L sodium selenite had the best effects on above physiological characteristics. The results showed that sodium selenite could improve Cd tolerance of maize seedlings by enhancing the antioxidant properties.