Abstract: Baihetan Hydropower Station is located on the borders of Sichuan and Yunnan provinces, China. It is the world's largest hydropower station under construction with the largest single-unit capacity. After completion, it will be the world's second largest hydropower station after the Three Gorges project in China. This paper systematically summarizes the main engineering geological problems in the dam site during the survey and design process, including:regional structural stability problem, asymmetric strong unloading problem, interbedded and intra-bedded dislocation zones problem, and columnar joint basalt problem. And we proposed corresponding engineering countermeasures and treatment measures, in view of the above major engineering geological problems, such as:by rationally adjusting the layout of the project and strengthening the support measures of the slope and caverns. We solved the influence of strong unloading, interbedded and intra-bedded dislocation zones on the stability of the dam foundation, slope and powerhouse complex. By adaptability design of arch dam structural combined with comprehensive control measures of excavation deformation, we solved the problems of columnar jointed basalt as the dam foundation rock mass. Baihetan hydropower station, as a typical high dam and large reservoir hydropower project, whose related research results can provide useful reference for the investigation and design of major projects in future.