This study was conducted to investigate the effects of chitosan-oligosaccharides on the growth performance, nonspecific immunity and antioxidant parameters of FFRC Strain Common Carp (Cyprinus carpio).The fish (mean initial weight: 33.90 ± 0.11 g) were randomly divided into 4 groups with 5 replicates per group and 15 fish per replicate.The fish were fed with either basal diet (control group) or basal diet supplemented 25, 50 and 100 mg/kg chitosan-oligosaccharides for 35 d, respectively.The results showed that dietary supplementation of chitosan-oligosaccharides did not significantly affect the growth performance and muscle composition of fish compared with the control group (P>0.05).As expected, dietary chitosan-oligosaccharide supplementation significantly enhanced the activities of plasma alkaline phosphatase (AKP).The similar effects were also observed on the concentrations of plasma complement 3 (C3) and complement 4 (C4) as well as the content of total iron binding capacity (TIBC) in plasma (P>0.05).In addition, dietary chitosan-oligosaccharide supplementation at 25 mg/kg also significantly enhanced the content of nitric oxide (NO) in spleen.The activity of myeloperoxidase (MPO) in spleen was promoted in fish fed chitosan-oligosaccharide at 50 (P<0.05) and 100 mg/kg (P<0.01).Dietary 50 mg/kg chitosan-oligosaccharide supplementation significantly increased superoxide dismutase (SOD) level and decreased the maleic dialdehyde (MDA) content in plasma (P<0.05).Based on the results above, it was indicated that chitosan-oligosaccharides could effectively improve nonspecific immunity and antioxidant parameters of FFRC Strain Common Carp (Cyprinus carpio) and the optimum level of 50 mg/kg exerted the best effects on FFRC Strain Common Carp in the present study.