To explore the effects on the growth and development and secondary metabolite content of Astragalus membranaceus var.mongholicus under under different water contents,and to lay a foundation for quality improvement of Astragalus membranaceus var.mongholicus and metabolism regulation mechanism.Methods:By using Astragalus membranaceus var.mongholicus as the test material,the test was conducted in the field.A total of 3 different drought treatments［regular soil-water content （CK），mild drought stress （A1），and strong drought stress （A2）］were applied to investigate the plant height,root length,commercial root length,fresh root weight and other characteristics of Astragalus membranaceus var.mongholicus under above different water stress.And the High Performance Liquid Chromatography(HPLC)was used to analyze the law of change of active components in Astragalus membranaceus var.mongholicus.Results:Under mild drought stress,the plant height of Astragalus membranaceus var.mongholicus was significantly reduced by 7.60% compared with the control group.But the root length was significantly increased by 11.23% and the fresh root weight was significantly increased by 26.07%.The commercial root length was significantly increased by 10.40%; under severe drought stress,plant height,root length,commercial root length and root fresh weight were significantly reduced compared with the control group,which were 13.67%,12.60%,17.05% and 5.5%,respectively.HPLC results showed that,the content of Calycosin-7-glucoside was 11.74% higher than that of control group under mild drought stress,however,the content of Calycosin-7-glucoside was 19.93% lower than that of control group under severe drought stress.The content of calycosin was not significantly different from that of the control group under drought stress.Conclusion:Mild drought stress can effectively promote the growth of Astragalus membranaceus var.mongholicus seedlings growing and improve the quality of the Radix Astragali seu Hedysari medicinal materials,so as to provide reference for the standardized planting technology of Astragalus membranaceus var.mongholicus.