Equal channel angular extrusion (ECAE) is a severe plastic deformation SPD) method for obtaining bulk nanostructured materials. The ECAE die consists of two equal channels that intersect at an angle, usually between 90o and 135o. . In the present study, the plastic deformation behavior of copper during the ECAE process with 120o die was investigated. To analyze the deformation behavior and the related strain distributions in the specimen, the commercial FE code ABAQUS has been used. The properties of the materials are strongly dependent on the shear plastic deformation behavior during equal channel angular extrusion (ECAE), which is controlled mainly by die geometry, material properties, and the friction between billet and the die. The ECAE process for these conditions was explained using the two different friction conditions of 0.15 and 0.01 to all sliding surfaces. The effective strain by the theoretical equation is in good agreement with the FEM results.