Theoretical studies of the milling tillage working body, in particular, dynamic properties under conditions of periodic external load, are substantiated and the main technological parameters are substantiated, and energy performance indicators are analyzed. The following data were adopted as the initial data for theoretical studies of the milling working body: the size of the row-spacing and strips, the dimensional characteristics of the root and stem residues. Theoretical studies of the milling machine gave such justified results: the diameter of the milling drum Dfr.bar = 0.3 m, the rotation frequency of the milling drum nfr.bar = 190 ... 430 hv-1, the number of installed knives on one disk n = 4 pcs, the rotating speed Vob = 6.59 m/s. Rational parameters and operating modes are justified: milling power Nfr = 19.3 kW, torque on the milling drum shaft Mkr = 0.45 kN·m. Theoretically substantiated milling working body is implemented in the development of a combined grinder of plant residues of thick-stem crops. The investigated working body, which performs the technological process of grinding compacted plant residues of thick-stemmed crops with the proposed technology, will allow us to further substantiate in more detail the mathematical model of the combined method of processing the field clogged with plant residues and determine the structural and technological structure of the grinder. The further development of the theoretical foundations of grinding plant residues and soil, in particular milling working bodies used in combined units, has been obtained.