Abstract: The filling height in the center of a section of an expressway is 16 m, the filling slope height in some sections is 18 m, the cross slope of the ground is gentle, the natural slope of the ground is 3°～ 8° , in the shape of steps, and the overall slope is about 7 ° . The groundwater is abundant, and the local bedrock is exposed as limestone, sandstone and mudstone. The rock slope is inclined to the ground slope with an inclination of 14° , The loading of the upper fill leads to the overall deformation of the subgrade and the formation of landslide. In this paper, the stability of filling slope with gentle ground cross slope is calculated and analyzed, and the influencing factors of slope stability and slope deformation characteristics are summarized. If the subgrade is filled on the ground where the bedrock is inclined, even if the filling height is small, it will still lead to the instability of the embankment and the sliding of the upper subgrade to form a landslide. Comprehensive treatment measures such as foundation treatment, gravel blind ditch, series water collecting well and anti slide pile have been adopted for the filling slope, and good results have been achieved.