The modulus of deformability in rock engineering is defined as the ratio of stress to the corresponding load deformation. This parameter is one of the most suitable parameters for indicating mechanical behavior before rock failure And plays a vital role in the economic design and safety of rock structures. In order to provide a proper relationship, first we have chosen the most suitable empirical relationships from existing relationships for in situ data. For this purpose, linear regression and four validation methods including RMSE, MARPE, ER errors and variance error method (VAR method) were used. In this research, by using available data and the statistical methods, the rock mass deformability modulus was evaluated. Finally, an empirical relationship was developed to evaluate the rock mass modulus. Validation of the relationship was evaluated by using in situ data. The proposed relationship was investigated by using available data and the RMSE error value was equal to 6.59. This error value is low compared to other empirical relationships. The proposed relationship was also compared with other empirical relationships And the results obtained from this study indicate a very good agreement between the proposed relationship with other empirical relationships