Abstract: Urban solid waste landfill-induced high-steep slope instability often leads to secondary disasters such as extensive building destruction and casualties. To quantitatively evaluate the disaster risk of artificial landfill landslides, this study takes Shenzhen’s “12.20” Guangming landslide as a case study, employing the depth-integrated method-based Massflow software to construct a dynamic numerical model that reproduces the entire evolution process of landslide initiation, high-speed movement, and deposition. By coupling with impact pressure calculation methods for landslide masses, the destructive impact effects on surrounding buildings were quantitatively evaluated. An uncertainty analysis framework was introduced, treating geotechnical parameters and sliding surface properties as random variables. A probabilistic analysis model was developed through Latin hypercube sampling, revealing the statistical characteristics of landslide travel distance under multifactorial influences and establishing a correlation model between landslide motion exceedance probability and building impact damage. Building vulnerability was further considered when conducting risk assessments for structures and nearby personnel. The study demonstrates that the depth-integrated method effectively captures the dynamic evolution of landslides, with simulated failure surface morphology, travel distance (1139m), and deposition pattern highly consistent with field monitoring data; impact pressure from landslide masses on buildings exhibits a rapid rise to peak values followed by gradual attenuation, with peak pressure decreasing significantly with distance from the landslide source; probabilistic analysis of landslide travel distance based on parameter uncertainty shows the actual deposition zone entirely falls within the 95% confidence interval, and building damage areas align with hazard zoning results. The proposed risk assessment framework integrating depth-integrated modeling and uncertainty analysis provides a novel methodology for quantitative evaluation of engineered landfill landslides, offering significant theoretical and practical implications for solid waste landfill safety management in the context of “zero-waste city” development.