Abstract: To clarify the effects of vitamin C supplement in diet on growth performance,tissue vitamin C levels and non-specific immunity indices of Cyprinus carpio,six vitamin C supplement groups at different levels:0(control),20,40,80,160,and 320 mg/kg were set in this study.The experiment period was 60 d.The results showed that weight gain rate(WGR) tended to increase with the increase of vitamin C supplement in diet(P < 0.05).No significant difference was found among specific growth rate(SGR) and survival rate(SR)(P > 0.05).Muscle and liver vitamin C concentrations showed significant differences among groups(P < 0.05),of which tended to increase firstly and then stabilize.Liver vitamin C concentrations were significantly higher than that of the muscle vitamin C concentrations(P < 0.05).Superoxide dismutase(SOD),catalase(CAT) and alkaline phosphatase(AKP) activity increased significantly(P < 0.05) when the vitamin C supplement in diet increased from 0 to 320 mg/kg.However,there was no difference in serum lysozyme(LZM) activity(P > 0.05).Superoxide dismutase(SOD),catalase(CAT) and alkaline phosphatase(AKP) activity of the 80,160,320 mg/kg groups were significantly higher than that of the 0,20 mg/kg groups(P < 0.05).In conclusion,adding vitamin C to diet could promote the growing development of Cyprinus carpio and enhance the non-specific immunity.