Abutment and foundation of dams need to investigate thoroughly from engineering geological point of view to get behavior of mass material. The essential part is the estimation of deformation modulus for rock mass which is indeed the heart of the matter for all geologist and geotechnician since the estimation of the modulus using the filed methods is expensive, time-consuming and difficult the modulus normally calculated using the relations suggested by rock mass classification systems. This method has been widely used in various projects. This research work while comparing the currently used classification system such as RMR, RMi, Q, GSI, tends to estimate get a reasonable estimation of the deformation modulus for Ghare Aghach rock mass using the available relation it has been observed that the Q-system evaluation of the rock mass is weaker than RMR while the Q shows the deformation modulus more than RMR. Also RMi and GSI show higher values of the modulus than other classification systems.