Abstract: Taken annual seedlings of Hedysarum mongolicum in Uxin Banner of Erdos as study material. The effect of different concentrations of paclobutrazol on the characteristics of aboveground growth and root of H.mongolicum was investigated under the severe drought condition. The results showed that plant growth was inhibited, while the branch diameter and tillering were enhanced at the paclobutrazol concentration changing from 150 mg/L to 600 mg/L under the severe drought condition. The root length, root volume and root superficial area were smaller than CK at the concentration of 150 mg/L, the root characteristics was promoted at the concentration above 300 mg/L. In the aspect of improving root length, radicel was most sensitive to paclobutrazol. Through correlation analysis and membership function analysis, the correlation between aboveground growth and root was not obvious, but the correlation among root characteristics was close. Paclobutrazol with a concentration of 450 mg/L has the best effect on improving drought resistance for H.mongolicum.