The application of mathematical methods is one of the most rational approaches used to solve tasks of evaluating the efficiency of unconventional metal forming processes. Using computer simulation in the DEFORM-3D application software package, we performed virtual full factorial experiments for the processes of producing individual samples by equal-channel angular pressing (ECAP) and highpressure torsion (HPT) from the Mg-1%Ca magnesium alloy, taking assumptions into account. At the stage of the simulation task preparation, it was accepted that the most significant factors that influence the fabrication of defect-free semi-products by severe plastic deformation (SPD) via ECAP are the processing temperature and the number of processing cycles via route Вс. In both models, strain intensity was taken as the response parameter. To simulate the SPD process of HPT, the processing temperature and the number of revolutions were used as the main variable factors. In the virtual full factorial experiment, the effect of independent factors on strain intensity was evaluated. As a result of the experiments, regression equations were obtained, variants of the rational processing regimes for the investigated alloy were presented, and their effect on the response parameter was analyzed. The proposed and implemented numerical models allow us to recommend the ECAP processing of the Mg-1%Ca magnesium alloy at a deformation speed of 1.0 mm/s and temperature of about 350 °С for 2 – 4 cycles, and the HPT processing under a hydrostatic pressure of 6 GPa at room temperature with the number of revolutions from 3 to 5.