Abstract: The Multipurpose hydropower project in Baise of Guangxi province includes a huge reservoir and a high dam and many rock caverns for underground powerhouse. They are built on the thin diabase dike with complex geological condition. The ground consists of poor integrity of the rock mass, deeply weathered rock in low-intensity of the upper and lower contact alteration zone. The foundation of stilling basin is uneven because weathered interface is buried deeply causing by a major fault developed in the diabase dike along the riverbed. So many geological problems were encountered. In the construction process, the different preventive measures were carried out to stablize the foundations of the buildings with different geological problems. Deep consolidation grouting was carried out to treat the upper and lower contact alteration zone. Deep cut and concrete backfill, strengthen consolidation grouting measures were carried out to treat the fault. Thickening the bottom layer, consolidation grouting and anchor processing were carried out to treat the foundation of the stilling basin. Tension bolt and cable reinforcement were carried out at the plastically deforming area of thin rock wall and the shallow buried section of the underground powerhouse. The project has been operating normally after the treatments. The observed data of the deformation of the dam foundation and the caverns, stress and osmotic pressure are within the design scope.