) is an important economic aquatic animal farmed in China, and is increasingly being exported as a worldwide food. is umami, sweet, and rich in nutrients. There is a lack of wild Chinese mitten crab that cannot meet the needs of increasing consumption. Therefore, determining the nutrient requirement for this crab is important for developing its aquaculture. Selenium is a component of the enzyme glutathione (GPx), which can protect cell membranes against oxidative damage. It also converts hydrogen peroxide and fatty acid hydroperoxides into water and fatty acid alcohol using reduced glutathione. However, the requirement for selenium of the Chinese mitten crab is unknown. Organic Se has higher bioavailability than the inorganic Se. Therefore, a 6-week feeding trial was conducted to investigate the effects of dietary Se supplementation on the growth performance, body composition and antioxidant status of juvenile Chinese mitten crabs. Six diets containing 0, 0.2, 0.4, 0.6, 0.8 and 1.0 mg/kg selenium were fed to quadruplicate juvenile Chinese mitten crabs (0.27±0.01) g, respectively, with 30 crabs in every aquarium. The results showed that juvenile fed the diet with 0.4 mg/kg(diet) Se supplementation obtained the highest weight gain, survival rate and whole body crude protein content among the various groups . Hepatopancreas and muscle selenium contents were positively related to the dietary Se supplementation. Both serum and hepatopancreas glutathione peroxidase activities increased with increasing dietary Se level, and peaked at 0.4 mg/kg(<0.05). When dietary Se increased to 0.8 mg/kg, serum glutathione peroxidase activity decreased significantly (<0.05). The highest serum glutathione reductase activity was observed in the crab fed diet of Se level 0.4 mg/kg (<0.05). The malonaldehyde content initially decreased and then increased with increasing dietary Se supplementation. Crabs fed the 0.4 mg/kg diet had the lowest malonaldehyde content, and differed from that of the control and 1.0 mg/kg groups(<0.05). Crabs fed a diet containing less than 0.6 mg/kg selenium had lower glutathione levels compared with crabs fed 0.8 mg/kg and 1.0 mg/kg (<0.05). The results indicated that dietary selenium supplementation of 0.4–0.6 mg/kg (total selenium of 0.43–0.66 mg/kg) can promote growth, use of dietary protein and anti-oxidative ability of juvenile Chinese mitten crabs. Quadrate broken line analysis with serum GPx showed that a level of 0.51 mg/kg selenium supplementation (total selenium is 0.59 mg/kg) could meet the optimal anti-oxidative status