Abstract: Basalt rocks at different geological conditions have a different structures. At first, if the rock is under in-situ confining pressure, the structure of the rock face has close mosaic, the rock has good integrity. The structural integrity of the rock face for rock structure evaluation does not have good correlation with the minimum distance of structural planes. The integrity of the evaluation index should be used. Secondly, if the rock is a state of stress relaxation. The rock integrity is poor. the structural integrity of the surface has a very good correlation with the minimum distance of structural planes. The minimum distance should be used as the evaluation index. This paper further uses the rock foundation of a hydropower station in southwest China as a case study. The rocks are under different environments. The rock structure is evaluated and the the rock integrity index is selected for the deep rocks. 