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