This study focuses on simulating the disaster impact of the 1920 Haiyuan earthquake. Utilizing a ground motion parameter attenuation model based on the shortest distance to the fault, it integrates records from different epicenters and magnitude intervals to simulate seismic intensity. A dual-model approach combined with multiple scenarios is employed to estimate casualties resulting from a recurrence of the earthquake, with simulation accuracy validated through comparison with historical seismic damage records. The results indicate that the intensity distribution calculated using the Lanzhou Earthquake Research Institute, China Earthquake Administration version of the Haiyuan earthquake epicenter location ang hypocenter depth combined with a magnitude of M_w8.3 aligns well with historical isoseismal lines, and the epicenter zone aligns with the direction of the surface rupture zone. The estimated casualties suggest that under current population density and economic conditions, if the earthquake were to recur, the death toll could still reach the 100,000 level, with the majority concentrated in areas with intensity levels of IX or higher. Insufficient seismic resistance of buildings in the epicenter zone, high population density, and secondary earthquake hazards are the primary factors contributing to casualties. Comprehensive measures such as avoiding active faults, enhancing building seismic standards, and optimizing emergency response plans are necessary to mitigate potential risks.