Methods of substantiation of a rational mining technology for the new potash horizon are presented in the paper. Progressive technological mining schemes for potash mining company «Belaruskaliy» are reviewed, as well as the geological conditions of the IV potash horizon. Basic aspects of the geomechanical substantiation of parameters of technological mining schemes for conditions of the IV potash horizon in the presence of influence of the overlying horizons are also presented. Results of modeling of the stress-and-state strain of the rock strata with production horizons are described.