Abstract: The South-North Water Diversion Project (SNWDP) is a world-attracted giant trans-basin water transfer project, which consists of three routes: the east route, the central route and the west route. Due to its large coverage that crosses several river basins, engineering geological conditions of the SNWDP are characterized by diversity and complexity. In particular, various and very complicated engineering geological problems, which are rarely encountered both in China and abroad, exist along the west route, due to its unique geographic location, climate, tectonic settings and scale. As a result, the geological investigation is a very difficult task. Properly solving engineering geological problems encountered in the SNWDP will not only meet the basic requirements for the timely completion of the project, but also advance the engineering geosciences and relevant technologies as well.