Abstract: Based on a mountainous 110 kV transmission line project, this paper optimizes differentiated construction of tower foundations and tower erection technology for narrow sites. It also introduces UAV-guided tension stringing technology and establishes supporting measures for mountain lightning protection grounding optimization and whole-process quality and safety control. Engineering practice shows that this complete set of technologies effectively solves construction bottlenecks under complex terrain conditions, reduces manual operation risks, and significantly improves construction efficiency and project quality. The proposed technologies provide reliable engineering experience and technical reference for the construction and quality control of similar transmission line projects under complex terrain conditions.