Abstract: Against the background of large-scale power grid construction in the loess regions of Shaanxi Province,transmission line corridor resources are becoming increasingly scarce.The conventional approach of avoiding existing old landslides for line routing is no longer suiTab.for the actual needs of engineering construction.Accurate evaluation of the stability of old landslides and scientific placement of tower foundations have become core technical challenges limiting the orderly advancement of transmission line projects in this region.To address these technical challenges,this study employs three-dimensional numerical simulation techniques for the stability of old landslide bodies and combines InSAR slope deformation monitoring data to conduct systematic experimental and analytical research.A comprehensive analysis is carried out on the stability evolution characteristics of old landslides under different relative positions between tower foundations and landslide bodies.The potential disaster risk levels of old landslides to tower foundations under various positional combinations are clearly defined,thereby accurately identifying relatively sTab.areas for tower foundation placement.The research findings can provide reliable theoretical support and data references for optimizing the route selection and scientifically designing tower placement schemes for transmission lines crossing old landslide zones in Shaanxi's loess regions.Additionally,the study offers solid theoretical foundations and technical support for the stability assessment of old landslides and structural design of transmission towers in the region,demonstrating significant practical engineering value and application prospects.