Abstract: In early stage of design work of PosoI HPP in Indonesia, the data provided by owner was less. It's hard to analyze the physical and mechanical properties of overburden and the engineering geological conditions. In order to solve the engineering problem, the field geological survey and borehole core appraisal have been carried out. According to field geological survey and analysis of borehole test data provided by the Owner as well as actual experience in China's projects, we have used engineering analogy method to propose recommended values of physical and mechanical parameters for overburden in the project area. The solution of engineering problem is worthy of reference for the similar project abroad.