It is believed, that uniform simple shear is realized during ECAE resulting in the uniformity of the stress-strain distribution and mechanical properties. However, some experimental facts as well as Finite Element simulation confirm a more complicated and non-uniform strain mode. Despite the increased efficiency of FE packages accounting for temperature, friction condition, tooling configuration and complicated constitutive models, the finite shear strain can not be precisely simulated by plastic flow or incremental models. The simple and precise analytical-experimental method for the direct evaluation of strain distribution during the shear deformation, namely the combined grid method was adopted in this study. This paper describes the theoretical principles, the grid patterns and the calculation of the strains based on the grid node displacements and calculation of stress resulting on integration of equilibrium equations along flow line xs.