In the Three Gorges reservoir area, the slope instability is often caused by the special engineering geological conditions and the influence of rainfall. Taking Jinjiling landslide in Jiangdong New District, Wushan County, Chongqing as an example, the characteristics of landslide deformation were obtained through the analysis of surface displacement monitoring data for many years. The seepage and stress coupling calculation method was used to analyze the seepage characteristics of slope under the action of drainage engineering by using finite element software. The results show that the deformation degree of Jinjiling landslide is not directly related to rainfall, and only the continuous and concentrated rainfall can cause the rise of groundwater level to produce obvious deformation of Jinjiling landslide. With the increase of drainage time, the groundwater level gradually decreases, the pore water pressure in the slope body gradually decreases, the displacement deformation area and the maximum displacement of the slope body decrease, and the stability coefficient gradually increases, but the growth range of the stability coefficient shows a downward trend. The research results verify that groundwater seepage is the main driving force to control the landslide deformation in Jinjiling, and the drainage measures have a remarkable effect on prevention and control, and the landslide is now in a stable state. It also confirms that the implementation of underground drainage tunnel measures in the water-rich slope is effective, and can provide reference for the disaster prevention and control of similar slopes.