Landslides along highway routes always interrupt traffic and endanger human life. In mountainous area, for the complexities in geology, vegetation cover and hydrological conditions, it's difficult to evaluate the stability of landslides along the highway. It has been recognized that landslides will occur in the same geological, geomorphologic conditions as in the past. Based on the back calculation of mechanical parameters of a past landslide site along a highway in the research area, this paper evaluates landslide stability and recurrence probability in this area to prevent similar hazards from happening again. In slope stability analysis, 2D methods are widely used in artificial slopes. But to natural slopes, especially in mountainous areas, section-line based 2D methods can't reflect 3D geological conditions of natural slopes. So, a GIS-based 3D slope stability method is used to calculate the mechanical parameters. Then, to locate possible landslides, the study area is divided into slope units. Through Monte-Carlo simulation and a 3D limit equilibrium models, the safety factors and failure probabilities of study area can be evaluated. Coupling terrain attributes and safety factors, the landslides in a watershed besides the highway are considered to have the most influence to highway.