Applying Sever Plastic Deformation (SPD) to metals in order to form a nanocrystalline structure in them has been the subject of many recent researches. Investigations show that the nanocrystalline structure improves mechanical properties such as the yield strength and wear resistance. Among the SPD methods, more attention has been paid to the High Pressure Torsion (HPT) and Equal Cannel Angular Pressing (ECAP) methods. Irrespective of different work-piece geometries produced through these methods, studying the amount of plastic deformation as well as the method of applying it could be useful in comparing these processes and choosing the more effective ones. In this article, the results of finite element analysis of the HPT and ECAP processes on pure commercial aluminum are provided and the rate of success of each process in applying the SPD to the part is studied. Plastic deformation is considered as a parameter for calculating the amount of grain refinement. The two methods are compared and their advantages and disadvantages are discussed in the end.