Abstract: The influences of relative parameters in the Hoek-Brown criterion, such as the maximum principal stress, minimum principal stress, geological strength index GSI and uniaxial compressive strength on the stability of surrounding rock of large underground caverns of hydropower stations are analyzed, and numerical calculation models and scenarios are developed to analyze the variation patterns of surrounding rock deformation and plastic zone depth in large underground caverns under the influence of above parameters.The results show that according to the variation patterns, the deformation and plastic zone depth of surrounding rock can be divided into three stages: basically unchanged stage, slow change stage, abrupt change stage.Based on the plastic zone characteristics of surrounding rock and deformation trend of caverns, the deformation and plastic zone of surrounding rock can be divided into self-stable region, controllable region and uncontrollable region.A Hoek-Brown criterion based the relationship between the geostress, strength of rock mass and stability of surrounding rock of underground cavern of hydropower stations is obtained.It is showed that the surrounding rock of the underground cavern corresponding to the self-stable region is in a stable or basically stable state.And for the controllable region, the surrounding rock has certain deformation or relaxation failure, but the deformation can be controlled or the stability of surrounding rock can be maintained under a certain supporting strategy.And for the uncontrollable region, the surrounding rock deformation or relaxation failure is more obvious, and the surrounding rock deformation or stability cannot be controlled under the general support strategy.According to the above relationship, the surrounding rock stability of underground caverns under the different geostress and different strengths of rock mass can be evaluated comprehensively, it can also systematically guide the whole process design and construction of underground cavern group.