Abstract: In order to reveal the mechanism of soil erosion resistance of Caragana Korshinskii roots, taking the Caragana korshinskii root-soil composite systems with low liquid limit clay, soft sandstone weathered soil and fine grained sand as the research objects, the shear strength and strength index of them and their differences were analyzed. The results showed that the shear law of the Caragana korshinskii root-soil composite systems under three different soils all obeyed the More-Coulomb strength failure criterion. At the significant level of 0.05, the shear strength of soil increased by roots at 12.5 kpa was better than that at 25 kpa. The shear strength, residual shear strength and the strength indices of the three Caragana korshinskii root-soil composite systems were all better than that of the corresponding plain soil. The order of shear strength, residual shear strength, cohesion and residual cohesion among the three root-soil composite system was presented by root-low fluid limit clay > root-soft sandstone weathered soil > root- fine grained sand. The order of internal friction angle and residual internal friction angle of them were showed by root- fine grained sand > root-soft sandstone weathered soil > root-low fluid limit clay. The growth ranges of cohesive force and residual cohesive force were 9.97%-45.78%, and the growth ranges of internal friction angle and residual internal friction angle were −4.09%-2.40%. Above all, the roots could enhance the soil shear strength and residual shear strength. The Caragana Korshinskii roots had the most obvious and the best effect on improving the shear properties of low liquid limit clay. The cohesiveness was an important role on increasing the shear strength and residual shear strength of the root-soil composite system.