As a result of computer simulation carried out using the DEFORM 3D software package, the influence of the shape of an extrusion die, combined with equal-channel angular pressing in parallel channels (ECAP-PC), on the stress-strain state of cylindrical billets of aluminum alloy was established. The obtained data made it possible to manufacture an experimental set for extrusion combined with ECAP-PC, and to produce a cylindrical long-sized UFG billet of the 6063 alloy in it. It has been established that one cycle of direct extrusion combined with ECAP-PC in the matrix with a non-axisymmetric deforming section for direct extrusion leads to significant microstructure refinement and improvement of mechanical properties of the alloy.