Abstract：Jinping first stage hydropower station is a concrete double-curvature arch dam with a maximum height of 305 m. It has a total capacity of 360×104 kW，the total reservoir capacity is 77.6×108 m3，and the regulating capacity is 49.1×108 m3. It is the highest in the world，and its design complexity is at the world¢s top level. In response to the low surrounding rock classification，developed structure planes，high geostress and massive underground cavern group，the 3D nonlinear elastoplastic damage finite element method is applied to analyze and compute the stability of underground cavern groups to make certain the rationality of the layout of underground cavern group，the sequence of construction and support parameters of surrounding rock. By analyzing and comparing the numerical simulation results and geomechanical model experimental data，it is indicated that the numerical simulation results agree well with the experimental data. The stability of the underground cavern group satisfies the requests of design.
