Abstract: When analyzing the rock mass of a underground nuclear waste repository,the current studies are all based on the loading mechanical condition,and the unloading damage of rock mass is unconsidered.According to the different mechanical condition of actual engineering rock mass of loading and unloading,this paper implements a comprehensive analysis on the rock mass deformation of underground nuclear waste repository through the combination of present loading and unloading rock mass mechanics.It is found that the results of comprehensive analysis and actual measured data on the rock mass deformation of underground nuclear waste repository are basically the same,which provide supporting data for the underground nuclear waste repository.