The stability of rock blocks is still a key problem in the rock excavation industry and therefore deserve further research and study. Due to the complicated nature of large-scale, three-dimensional developments in blocky rock masses, it is critical to conduct investigations into the stability of rock blocks and choose a reasonable excavation and rock-supporting scheme for design and construction purposes. This article introduces the basic analysis procedure of the General Block (GB) method and discuss the stability of rock blocks in an underground hydropower station at the Three Gorges Project. The application of the GB method mainly follows four basic steps: the discretization of the domain; removal of incomplete fractures; block identification and finally, the block stability analysis. Block identification is the most important of the four processes. A 3-D block model is set up and analyzed. The results from the analysis is used to evaluate the stability of the surrounding rock mass in the powerhouse during the process of excavation. The findings provide guidance on the excavation process and the support requirements for the underground power station. It is envisaged that model study will serve as a reference for the stability evaluation of rock blocks in some related fields.