Abstract: Isatis indigotica Fort.was used as experimental materials,the seedlings were treated with100mmol·L^-1 NaCl solution,the concentrations of 0,3,6,9,12mmol·L^-1 exogenousγ-aminobutyric acid were sprayed on the leaves,the content of reactive oxygen species（ROS）and antioxidant enzyme activities were determined in the seedlings in order to provide reference for enhancing salt tolerance of Isatis indigotica Fort..The results showed that the ■productive rate and H₂O₂content in seedlings under NaCl stress were significantly increased,increasing by 120.73%and 113.09%compared with the control group.Spraying on the leaf 9 mmol·L^-1 of exogenousγ-aminobutyric acid,the ■productive rate and H₂O₂ content in NaCl stress reduced by 30.69%,41.10%,superoxide dismutase（SOD）,peroxidase（POD）,catalase（CAT）and ascorbic acid peroxidase（APX）activity increased83.47%,42.38%,34.80%and 76.91%.Under NaCl stress,exogenousγ-aminobutyric acid concentration was negatively correlated with ■productive rate and H₂O₂ content,exogenousγ-aminobutyric acid concentration was positively correlated with the activities of superoxide dismutase（SOD）,peroxidase（POD）,catalase（CAT）and ascorbic acid peroxidase（APX）activity.According to the comprehensive analysis,the effects of exogenousγ-aminobutyric acid on relieving NaCl stress was 9 mmol·L^-1＞6mmol·L^-1＞12mmol·L^-1＞3mmol·L^-1.