Evolution of dislocation cell microstructures during severe plastic deformation was analyzed using a modified kinetic dislocation model based on the two dimensional approach by ETMB [Y. Estrin, L.S. Tóth, A. Molinari, Y. Bréchet, Acta Mater. 46 (1998) 5509]. The proposed model simulated decreasing dislocation density after a maximum point and increasing misorientation angle with strain, which fits with experimental results well.