With the upgrading and transformation of national energy strategies, the western region abundant in hydropower resources has become a critical carrier for engineering construction. Consequently, there is an urgent need to conduct meticulous investigations of geological characteristics in construction areas to support engineering planning and implementation. To address challenges including unclear laterally distributed lithological features, ambiguous geological attributes, and imprecise fault distribution descriptions in this region, the long-distance horizontal wire-line core drilling technology was employed for refined geological exploration. Through optimized selection of advanced equipment and formulation of efficient drilling techniques, a key technological system for long-distance horizontal wire-line coring was established, achieving the objective of precise geological and structural characterization in target areas. Taking a geotechnical investigation project in western China as a case study, the application of this core technological system demonstrated remarkable performance: an average drilling rate of 3.61 m/h, monthly drilling efficiency reaching 422.42 m per rig, terminal hole inclination deviating merely 0.1% from design specifications, full-hole azimuth maintained within ±1° of planned values, and core recovery rate exceeding 94%. Field applications confirmed that the proposed key drilling technology exhibits significant guiding value for engineering surveys in western regions, providing scientific basis for resource exploration and development in complex geological terrains.