S. miltiorrhiza is a Chinese medicinal plant that is widely cultivated. The root growth in S. miltiorrhiza are inhibited by soil salinity. Here we investigated the capability of a plant growth regulator, 5-ALA to promote the growth of S. miltiorrhiza under different salt stresses. Five-month old S. miltiorrhiza roots were uniformly irrigated with different levels of salt solution i.e. 0, 100, 200 mM NaCl. After 3 days of treatment, salt-treated S. miltiorrhiza plants were sprayed with different concentrations of ALA (0, 10 mg L-1, 20 mg L-1) on the leaves and cultured for another 7 days. Results revealed that ALA treated plants produced significantly higher biomass by sustaining leaf chlorophyll content under salt stressed. 10 mg L-1 ALA significantly up-regulated antioxidant enzymes activities under studied salinity treatments. Positive effects of ALA on antioxidant defense systems were also supported by a significant increase in the expression of SOD isoenzymes genes (CSD1, FSD1 and MSD2), defense response genes (DXS1, C4H, GGPPS) and stress-related gene (MYB36 , MYB39) of ALA treated plants. This study suggested that ALA can protect S. miltiorrhiza from salinity induced oxidative stress and injury by promoting antioxidant defense system, boosting secondary metabolic pathways and protecting photosynthetic pigments.