Due to prolonged rainfall, a landslide disaster occurred on August 21, 2020 in Zhonghai Village, Hanyuan County, Sichuan Province, resulting in casualties. Through extensive on-site investigation and analysis of landslide characteristics, a numerical simulation of the landslide movement process was conducted with MatDEM software. Findings indicate that the Zhonghaicun landslide is a medium-sized landslide formed within the Xigeda Formation stratum. The continuous rainfall weakened the sliding surface's strength and caused its deterioration, which was the primary triggering factor of the landslide. The landslide movement process can be classified into three stages, which are starting-sliding impact, moving scraping shovel, and accumulation stop. The secondary impact of the sliding source area on the impact-sliding area led to further expansion of the landslide's range. The total dissipation of gravitational potential energy during the movement process was 8.141 × 1011J, while heat energy from frictional forces was 8.117 × 1011J. Most of the landslide's gravitational potential energy was converted into frictional heat energy between individual particles. These research results are highly significant for the prevention and control of landslide disasters in the semi-diagenetic strata of the Xigeda Formation.