Abstract: The representation elementary volume (REV) was introduced on the base of the hypothesis of macro-continuity of rock masses. Firstly, the basic mechanical parameters of rocks were measured by the conventional triaxial tests and unloading resilience tests, and the mechanical parameters of rock interfaces and joints were obtained by direct shear tests. Secondly, the existence and the dimension of REV were determined by the method of numerical simulation testing according to the rule that the mechanical character can get to be stable when the volume of rock masses are larger than the dimension of REV. Finally, the mechanical parameters of rock masses were calculated by numerical simulation analysis of a three-dimensional model based on the dimension of REV.