Caverns are the biggest structure made by human being in the ground, which is built for different purpose.During Excavation as it is possible, Fracturing and loosening rocks surrounding underground openingShould reach minimum .there are a lot of coefficient and parameters which affect stability of rock mass ,and it is better to specify importance of these parameters. Priority the parameters can change with regard to mechanical characterizesThe rock mass or different rock mass behavior .Dam and storage Azad pumped-storage power plant is located in west Kurdistan province, Considering geological conditions rock mass characterizes and high amount calculations, two dimensional Phase2 program is utilize to model and analysis sensitivity .After analysis the maximum displacement, define the most length plastic zone in the area the Azad power plat cavern and specify the position which tolerate the maximum force in Rock bolts .Totally seven points are choice for sensitivity analysis of parameters. Sensitivity analysis is done on effect changeable parameters such as deformation modules, horizontal stress coefficient, cohesion and friction angle. The sensitivity analysis results regarding plastic zone show that deformation modules and friction angle are the most important parameters on structure the most value of sensitivity in left abutment is 3.23 which relates to friction angle. The sensitivity analysis results with regard to deformation show that most value is relates to friction angle and equal to 1.43 for floor .With increase the horizontal stress coefficient, the plastic zone decrease in floor and increase in abutments also Sensitivity left abutment is for more right abutment which is mostly for geometry the cavern. The sensitivity of deformation parameters is approximately the same in different points. The least sensitivity is related to cohesion the rock mass.