Abstract: As rainfall infiltration is one of the main causes of landslides, studying the seepage law of slopes under different rainfall conditions can provide scientific reference for slope control. The slope of Nanshan Tunnel is dominated by water-sensitive soil, and the physical and mechanical properties before and after water contact are very different, and under irrigation or rainfall conditions, the existing engineering technology will cause water infiltration, resulting in increased slope weight and attenuation of rock and soil strength, which is not conducive to slope stability. With the help of GeoStudio software, the characteristics of rainfall infiltration law of slope under the action of plantable water interception blind ditch are simulated, and the following conclusions are obtained. Under other conditions being equal, with the increase of rainfall intensity, the position of the local saturation zone formed in the slope body gradually moves away from the slope during the water seepage process. When the rainfall shows an increasing trend with time, the position of the local saturation zone formed by the slope does not change much with time when the rainfall intensity is small, and there is a certain trend of slow upward movement. With the gradual increase of rainfall intensity, the position of the local saturation zone showed a downward trend. When the rainfall decreases with time, the position of the local saturation zone formed by the slope increases with time under the condition of large rainfall intensity, and there is a clear upward trend. With the decrease of rainfall intensity, the position of the local saturation zone also showed a certain downward trend. Through the simulation process, it can be seen that the plantable water interception blind ditch maintains a constant volume of water content in the nutrient soil under the five rainfall conditions established, which can provide a good growth environment for slope protection vegetation. At the same time, the water on both sides of the blind ditch always keeps moving into the ditch, and the water entering the ditch always maintains the trend of migration and excretion to the bottom of the ditch, which has good water interception and drainage capacity.