To investigate the effects of chlorogenic acid on the antioxidant activity and resistance to low-salinity stress in , 360 shrimps were randomly divided into four groups and fed four diets containing 0, 100, 200 and 400 mg chlorogenic acid/kg(diet). After feeding for 28 days, all shrimps were subjected to an acute salinity change from 32 to 10 for 72 h. Total antioxidant status (TAS), glutathione peroxidase (GPx) and catalase (CAT) levels, and expression of the , were analyzed. The results demonstrated that supplemental chlorogenic acid had no effect on TAS or on GPx activity in the hepatopancreas when shrimp were cultured in natural seawater. Compared with the D0 control group, however, dietary supplemental chlorogenic acid significantly increased GPx and CAT activities, and expression of the gene in the hepatopancreas after feeding the shrimp for 28 days ( in the D2 group [200 mg (chlorogenic acid)kg(diet) ] were higher than in the other groups, at 164.29 U/mg(prot) and 1.61 and 2.14 fold, respectively. After low-salinity stress for 24 h, the antioxidant response was characterized by higher TAS, greater GPx activity and higher gene expression of , i.e. an increase of 31.30%, 27.96% and 170%, respectively. Moreover, TAS, GPx activity and gene expression in the hepatopancreas in shrimp that were fed diets supplemented with chlorogenic acid were lower than those of the D0 group (. The results indicate that chlorogenic acid could effectively inhibit dramatic changes in antioxidant enzyme system activities of shrimp exposed to low-salinity stress. After low-salinity stress for 72 h, TAS, GPx and CAT activities and gene expression in the hepatopancreas of shrimp that were fed chlorogenic acid were higher than the D0 group. In conclusion, chlorogenic acid induces antioxidant system activity and plays an important role in resistance to low-salinity stress in .