Abstract: In order to investigate the influence of plant roots on slope stability under load conditions in the loess area of the Xining Basin, the Changlinggou watershed in the Xishan Mountains of Xining Basin was used as the experimental area in this study, the herb Elymus nutans and shrub Caragana korshinskii that suitable for the growth of the local climate environment were selected as the test species. Three planting schemes on the slope surface, i.e. single herb(Elymus nutans), shrub(Caragana korshinskii) and the combination of both were adopted. By applying a load on the top of the slopes, and disposing displacement meters and earth pressure boxes at different positions of slopes, the characteristics of soil displacement and earth pressure were analyzed. On this basis, the shear tests were carried out on the root-soil composite system of slope vegetation, and the shear strength and variation characteristics of the root-soil composite system at different positions of the slope under loading conditions were analyzed. The results showed that the cohesion of the root-soil composite system at the same position of slopes was greater than that before loading, and the cohesion of the root-soil composite system of the three kinds of plant slopes was greater than that of the slopes of soil without roots under the same conditions. Before loading, the density, moisture content, and internal friction angle of the four types of slopes at the same depth below the surface did not show significant differences (P<0.05), and the density and moisture content decreased with the increase of sampling depth. The density of Elymus nutans slope, Caragana korshinskii slope, the slope of soil without roots and combination planting slope at 0-10 cm below the surface was higher than that at> 20-30 cm, and the water content decreased by 21.31%, 16.13%, 19.47%, and 23.04% respectively. Compared with the slope of soil without roots, the root-soil composite system cohesion of the composite vegetation slope increased by 111.57%-136.50%, the herb slope increased by 69.62%-88.73%, and the shrub slope increased by 67.40%-84.27%; the root-soil composite system cohesion of the composite vegetation slope was significantly higher than that of the slope of soil without roots(P<0.05). Under the loading conditions, the density, moisture content and cohesion of soil increase compared with those before loading, and the increased ranges of slope of the soil without roots were 1.45%-2.80%, 1.09%-3.59%, and 7.75%-9.25% respectively. The density, moisture content and cohesion of herbaceous, shrub and composite vegetation slopes increased by 0.71%-2.05%, 0.66%-9.79%, and 0.65%-0.68%, 3.33%-7.55%, 4.19%-4.59% and 4.45%-8.13%, 3.79%-7.25%, 3.25%-6.95% and 2.63%-3.97%, respectively. Under the maximum loading condition, compared with the slope of soil without roots, the vertical displacement of the slope with combined vegetation, the slope with herb vegetation and the slope with shrub vegetation decreased by 58.81%, 44.80% and 28.41%, and the horizontal displacement decreased by 62.20%, 48.66% and 31.71%, respectively. The combined vegetation with herb and shrub had a greater inhibitory effect on the shallow displacement of the slope. The research results have certain theoretical research value and practical significance for the scientific and effective prevention and control of soil erosion, shallow landslide and other geological disasters in alpine, and semi-arid areas.