The object of the study is the process of separation of seed material according to the seed density on the working surface of the pneumatic sorting table. The main defining design variables and linkage parameters of the equipment are analyzed, which realizes the process of separation of seed materials, and is coordinated with physical and mechanical variables of raw materials. The principles of modeling of seed material layer movement as a multiphase medium are provided. Under the effect of working surface vibrations and the power of an airstream the layer take on the properties of pseudoliquid. The criteria of chosen variables are presented, on which depend quality and quantity indicators of the separation process of seed materials according to the seed density. Optimal values of the separator linkage parameters are analytically determined and dependence diagrams are built. Secant lines of surfaces for a concrete crop (raw material) are performed. The “purity” of heavy fraction during the variation of indicated parameters is studied. It is proved that there are differences in types of the dependences: different decreasing of functions and increasing of airstream velocity. It is obvious that this nature is determined by difference in density of original raw materials. This way the smallest influence a change in the air-stream velocity causes to soybean raw material, as soybean has the biggest density. At the same time, the biggest affect is provoked on sunflower seeds, which have the smallest density among the used types of raw materials, as well as a triangle form. It is determined that the maximal frequency of the basic fraction, gained by the separation of wheat seed material on PST, is obtained under the airstream velocity in the range 1.3-1.5 m·s−1. For corn the rational air-stream velocity falls in the range 1.3-1.6 m·s−1, for sunflower – 1.2-1.4 m·s−1, for soybean – 1.2-1.4 m·s−1. These figures are valid under the condition of using the relevant rational decisions of frequency and amplitude of vibrations of pneumatic sorting table deck during the separation of grain mixtures, as well as longitudinal and transverse angles of inclination. The veracity of experimental studying results is proved by the corresponding theoretical models of the process.