Abstract: The effects of chitosan on antioxidant enzymes and CuSOD gene expression level in rat liver were analyzed in this study.The chitosan were supplemented to rats that were given swimming training at three dose levels 0.5 g/kg,1.0 g/kg and 2.0 g/kg.The activities of antioxidant enzymes and CuSOD gene expression level in rat liver were measured after eight weeks acute exercise.The activities of antioxidant enzymes were all increased among chitosan supplemented groups compared to non-supplemented exercise rats.SOD,CAT and GSH-Px at 0.5 g/kg supplementation level were increased significantly compared to non-supplemented exercise rats(P<0.05).The activities of these three enzymes at 1.0 g/kg and 2.0 g/kg supplementation levels were increased significantly(P<0.01) compared to non-supplemented exercise rats.The MDA concentration were much lower than non-supplemented exercise rats(P<0.01).The results shows that the activities of antioxidant enzymes in rat liver were improved significantly by insect chitosan supplementation,and the gene expression level was consistent with the SOD activity increase.It suggests that the mechanism of improvement on antioxidant enzymes activities by insect chitosan was probably an increase result of their encoded genes expression level.