Multiple active faults are developed in the near field of the Majiishan Grottoes, with the northern margin fault zone of the West Qinling Mountains historically posing the greatest seismic threat. To investigate the impact of near-field seismogenic faults on the Majiishan grottoes, the seismic geological conditions and potential seismic hazards of the northern margin fault zone of the West Qinling Mountains were analyzed in this study. Combining the elastic dislocation theory and the three-dimensional finite element numerical simulation, the displacement and strain distribution patterns on the surface of the Majiishan Grottoes area during left-lateral strike-slip activities along the Tianshui—Baoji segment of the northern margin fault zone of the West Qinling Mountains under M 7.0 and M 7.5 earthquakes were examined. The results reveal that seismic deformation of the Tianshui—Baoji fault is dominated by horizontal shear, with localized secondary vertical deformation. Higher magnitudes significantly increase the magnitude and spatial extent of displacement and strain. In the Majiishan Grottoes area, seismic displacement, normal strain, and shear strain increase with the increase of magnitude. The southeastern direction of the grottoes exhibits the most critical displacement under future earthquakes, with shear strain posing the primary risk for potential rock mass dislocation or localized shear failure. Additionally, fault plane dimensions influence computational results: surface deformation stabilizes when the fault plane depth reaches 15 km, which can serve as a reference value for seismic simulations of the Tianshui-Baoji fault. This study provides critical insights for seismic risk assessment and mitigation of the Majiishan Grottoes.