In order to study the influence of the structural plane on the mechanical parameters of the broken rock mass, taking the construction of the underground powerhouse of Liyang pumped storage power station as an example, on the basis of the study of the geological conditions of the surrounding rock, the structural characteristics of the rock mass and the quality classification of the rock mass, the density, trace length and dip angle of the three cracks in the roof arch, the upstream side wall and the downstream side wall of the main power plant were selected for statistics, and the discrete fracture network was constructed based on Monte-Carlo method. Finally, the influence of discrete fracture network on the mechanical parameters of rock mass was studied by triaxial compression test discrete element simulation. The test results show that the structural plane plays a decisive role in the mechanical properties of the rock mass, and the parameters and discreteness of the uniaxial compressive strength, elastic modulus, cohesion, internal friction angle of the rock mass are more sensitive to the changes of the density, dip angle and trace length of the structural plane.