Abstract: Highway slope hazards represent a significant hidden risk to the safety of transportation infrastructure in mountainous areas. Scientific identification of their dominant controlling factors is key to disaster risk assessment and prevention. Taking Miyun District of Beijing as the study area, this research systematically analyzed the dominant controlling factors of highway slope hazards and their quantitative influence based on the Certainty Factor Method. First, based on the detailed analysis of the geological environment conditions and the characteristics of disaster historical data in Miyun District, the potential factors affecting slope stability were screened out. Then, using the statistical principle of the Certainty Factor model, the correlation coefficients (CF values) between each factor and slope hazard occurence were calculated to assess the "promoting" or "inhibiting" effects and contribution of each factor. Furthermore, a sensitivity index was employed to evaluate the degree of influence of each factor on hazard occurrence, thereby identifying the dominant controlling factors and disaster-prone zones. The results shows that there are nine main controlling factors of highway slope hazards in Miyun District, ranked by influence as follows: highway disturbance intensity, land use type, normalized difference vegetation index (NDVI), distance from the water system, elevation, topographic relief, engineering rock group, distance from the fault and slope, among which the four factors of highway disturbance intensity, land use type, NDVI and distance from the water system exert the greatest influence. This study achieves a quantitative analysis of the dominant controlling factors of highway slope hazards in Miyun District using the Certainty Factor model, providing a scientific basis for regional hazard risk zoning and optimization of prevention and control measures, and also provides a methodological reference for slope hazard studies in similar geological environments.