We studied the effects of exogenous 5-aminolevulinic acid(5-ALA)on germination of seeds,the content of soluble sugar,malondialdehyde(MDA)and antioxidase activities in Isatis indigotica seedlings under salt stress with sand culture.The results showed that:(1)There were significant inhibition of seed germinating and seedling growth in 100 mmol·L^-1 of NaCl stress.Germination rate,germination vigor,germination index,vigor index of seeds and water content were significantly decreased under salt stress,while malondialdehyde (MDA),content of soluble sugar,Cu-Zn superoxide dismutase (SOD)and peroxidase (POD) activies were increased significantly.(2)Under salt stress,appropriate concentration ALA could improve germination rate,water content,activities of SOD,POD and CAT,meanwhile reduce the contents of soluble sugar and malondialdehyde (MDA),in which the germination rate and germination vigor of seeds were the maximum,and the activities of SOD,POD,CAT were the maximum by the treatment of 16.7 mg·L^-1 ALA.It indicated that salt stress could obviously inhibit the seed germinating and seedling growth.Appropriate concentration ALA could effectively alleviate the damage to seed germinating and seedling growth of I.indigotica under salt-stress and promote the salt resistance,especially the effect of 16.7 mg·L^-1 ALA was the most significant.