Abstract: Studying the development and evolution characteristics, as well as the disaster-forming motion processes of typical geological disasters along the trunk highways in strong earthquake mountainous areas is significant for disaster identification and evaluation and the work of highway disaster prevention and reduction. Based on multi-source geological analysis methods such as field survey, remote sensing interpretation and GIS spatial analysis, this paper comprehensively considers the impacts of the 2013 and 2022 Lushan multi-phase seismic events, studies the development rules and evolution characteristics of co-seismic geological hazards along the Baoxing section of National Highway 351 in the earthquake area. On this basis, three-dimensional two-phase material point method (MPM) was used to analyze the disaster movement process of the high-level accumulation landslide in Xinhua Village. The key technologies for scenario deduction of high-level landslide disasters on main highways in earthquake prone areas were discussed. The results showed that: (1) In the study area, there were a total of 215 co-seismic geological hazards developed in 2022.They were mainly distributed within the 1500m elevation range of the bank slopes on both sides of the Donghe River Valley and a slope range of 30° to 50°. The common distribution characteristics of co-seismic geological hazards in 2013 are that the high-steep slope section of hard rock is a high-incidence area for disasters. (2) The development and distribution of co-seismic geological hazards in 2022 were mainly controlled by factors such as topography, river, and faults, and the spatial coupling with the epicenter location was not particularly strong. The hazard points that have significant impact on the highway were mainly developed near the protruding mountain parts with multiple exposed surfaces and fault zones, and were significantly affected by multi-period earthquakes superposition and historical rainfall. (3) The high-position landslide in Xinhua Village was affected by the superposition of multi-period earthquakes, rainfall, freeze-thaw cycles. In the past decade, it has shown a gradual backward deformation that continues to expand upward. Eventually, under the action of strong earthquakes in 2022, the overall large-scale instability occurred and the river channel was blocked. The three-dimensional two-phase MPM simulation reproduced the entire process of landslide movement, water inflow surge, accumulation and dam formation. The results showed that the landslide body was about 760,000 m³, with a maximum movement distance of about 609 m and a surge height of up to 8 m. The accumulation shape after simulated landslide movement was basically consistent with the actual situation on site. The research results provide theoretical and technical support for pre disaster risk assessment and post disaster construction of main highways in strong earthquake mountainous areas.