Abstract: To investigate the stability of unsaturated soil slopes under rainfall conditions with vegetation roots, this study is based on a rainfall infiltration analytical model that can calculate the distribution and variation of pore water pressure at any depth of the soil layer at any time. Through theoretical analysis, the effects of rainfall infiltration, tensile strength of vegetation roots, root area ratio, and growth direction of roots on the stability of shallow slope sliding were studied. The results indicate that the greater the tensile strength of the plant roots or the larger the root area ratio, the stronger the slope stability. Meanwhile, as the slope angle increased, the reinforcing effect of vegetation on the slope stability becomes more apparent. In addition, the growth direction of vegetation roots also has a significant impact on the reinforcement effect. In practical engineering, it is recommended to select vegetation with well-developed roots, longer growth, and a larger root area ratio while controlling the growth direction of vegetation roots to achieve a better slope protection effect.