Abstract: Potted Citrus. junos cv. Ziyang Xiangcheng seedlings were used to study the effects of selenium (Se) valence states (Se⁶⁺ and Se⁴⁺) on plant growth and antioxidants and antixodases in ascorbate(AsA)-glutathione (GSH) cycle. The results showed that Se⁶⁺ and Se⁴⁺ (from 1.0 mg·L^-1 to 8.0 mg·L^-1) stimulated the seedling growth by increasing plant height, leaf areas, and fresh or dry mass. Applying Se⁶⁺significantly increased plant Se levels mainly in leaf, and applying Se⁴⁺ slightly increased Se content mainly in root. Certain valence states and concentrations of Se increased leaf chlorophyll and hydrogen peroxide (H₂O₂) content. Se⁶⁺≤2.0 mg·L^-1 treatments enhanced the activates of glutathione reductase (GR) and glutathione peroxidase (GPX), and the contents of GSH and oxidized glutathione (GSSG), while Se⁶⁺≥4.0 mg·L^-1 treatments reduced the antioxidant contents and antixodase activities of GSH cycle. Moreover, Se⁴⁺≤ 2.0 mg·L^-1 treatments increased the activities of dehydroascorbate reductase (DHAR) and ascorbate peroxidase (APX), and resulted in higher AsA/[AsA+dehydroascorbic acid (DHA)] ratio. When Se⁴⁺≥4.0 mg·L ^-1, the antioxidant contents and antixodase activities of GSH cycle were increased. Together, this study showed that different valence states and application concentrations of Se showed different influences on AsA-GSH cycle in citrus, and 2.0 mg·L^-1 Se⁶⁺ and 4.0 mg·L^-1 Se⁴⁺ were the best concentrations for plant growth.