Abstract: In western of China, the topographical geological conditions are complex. For the slopes with broken rock mass and fracture development, the preliminary geological survey and experimental work can only obtain limited engineering geological information. With the excavation of the slope construction, the engineering geological information is gradually revealed. In this paper, a three-dimensional elastoplastic finite element model is established to meet the engineering geological characteristics, and the stability of rock slope is effectively analyzed. Computational analysis of the rock mechanics parameters of the engineering rock mass was performed by simulating the slope excavation process, and the displacement deformation was obtained by the inclination monitoring during the excavation process. The sensitivity analysis of the rock mass parameters was well done,and the back analysis and calculation of the rock mass mechanical parameters were obtained, which was close to the actual The optimal calculation parameters of the situation and the stability of the slope were analyzed. The results show that the slope stability analysis based on elastic-plastic finite element method is effective and feasible, and the variation characteristics of rock mass displacement field and stress field can be calculated to reveal the internal mechanism of slope excavation deformation. This study provides a new method for information construction design under complex geological conditions.