This experiment was conducted to investigate the effect of astragalus polysaccharides (APS) on antioxidant and nonspecific immune indices of yellow catfish (Pelteobagrus fulvidraco). Five hundred and forty 2-year-old and healthy yellow catfish were randomly divided into 6 groups with 3 replicates per group and 30 fish per replicate. Yellow catfish in the 6 groups were fed basal diets with 0 (control group), 300, 600, 900, 1 200 and 1 500 mg/kg APS, respectively. The experiment lasted for 8 weeks. At the end of the experiment, the activities of superoxide dismutase (SOD), catalase (CAT) and lysozyme (LSZ), the contents of malondialdehyde (MDA) and nitric oxide (NO), phagocytic percentage (PP), phagocytic index (PI), and disease resistance indices were determined. The results showed as follows: compared with the control group, the head kidney SOD activity in the 300 mg/kg APS group and the muscle SOD activity in the 600 and 900 mg/kg APS groups were increased by 1.61 (P<0.05), 1.95 (P<0.05) and 2.08 (P<0.05) times, respectively. The CAT activity in heart, liver, spleen, muscle and gill was significantly enhanced when supplemented with 600 to 1 500 mg/kg APS in diets (P<0.05). The CAT activity in head kidney and mesonephros in all APS groups was significantly higher than that in the control group (P<0.05). Compared with the control group, the MDA activity in liver and spleen in the 300 to 1 500 mg/kg APS groups and the MDA activity in heart, head kidney, mesonephros, muscle and gill in the 600 to 1 500 mg/kg APS groups were significantly increased (P<0.05), while the NO content in heart, liver, spleen and head kidney in all groups and the NO content in head kidney and mesonephros in the 600 to 1 500 APS groups were significantly decreased (P<0.05). When supplemental levels of APS ranged from 0 to 1 200 mg/kg, the LSZ activity was proportional to APS supplemental level, and the LSZ activity in all tissues was significantly higher than that in the control group (P<0.05). With increasing APS levels, the PP and PI were significantly increased (P<0.05). APS could decrease the mortality rate and enhance the protective rate when fish were over attacked with Edwardsiella tard, and the protective rate in the 1 200 and 1 500 mg/kg APS groups reached 50.0%, respectively. It is suggested that proper amount of APS supplementation in diets can enhance antioxidant of yellow catfish; additionally, 1 200 mg/kg APS supplementation has the greatest effects on enhancing nonspecific immunity function of yellow catfish.［Chinese Journal of Animal Nutrition, 2011, 23（9）：1622 -1630］