The Ms6.4 Yangbi earthquake occurred in Yunnan Province, the southwestern part of China. Under the influence of severe seismic motion, slopes were damaged and lots of tensile cracks appeared on the slope surface. Considering the potential further failure of damaged slope in the post-earthquake rainy season after Yangbi earthquake, the stability analysis of damaged slope is necessary to be carried out to evaluate its safety in the following rainy season. Through field investigation including UAV shooting and ERT measurement, the surface topography and subsurface geological condition of the damaged slope are obtained based on DEM and resistivity profile. The numerical mesh model of the damaged slope is built using mesh model reconstruction method with tetrahedron element. By using the result of DEM and ERT to define the geometry of upper gravel soil elements, a mesh model considering the damage characteristic of damaged slope is reconstructed. The stability of the damaged slope was calculated by the strength reduction method. The results show that the deformation is concentrated on the rear edge of the damaged slope, and the upper part above the excavation area of damaged slope may lose stability during the following rainy season. The results of numerical calculation are verified by the phenomenon observed in the investigation after post-earthquake rainy season, indicating the validity of reconstructed mesh model using DEM and ERT.