Stable situations of three kinds of excavated cavities of Shuibuya Hydropower Station under the action of crustal stress were detailedly researched by using geology mechanics model. The study includes three kinds of schemes, i.e., without processing, soft rock replacement and reinforcement with anchor piles and anchor ties, for which the stresses, deformations, overload failure forms and overload safety coefficients were compared. The achievement indicates that: the stability of without processing scheme is worst, the maximum tensile stress 1.44 MPa, deformation 29.1 mm and the overload safety coefficient 1.75; for soft rock replacement scheme, the overload safety coefficient is 2.5; the overload safety coefficients is 2.6 for reinforcement project. From research result, the technology of cavity excavation of the underground plant of Shuibuya Hydropower Station is feasible. The effects of two the soft rock replacement scheme and the reinforcement with anchor piles and anchor ties project are obvious. This two schemes can guarantee the security and reliability of the underground plant.