The aim of the work was to reduce the damage to the ears of sweet corn in the separation due to the justification and optimization of the geometric parameters and kinematic modes of operation of the cob separating machine of corn harvester. Theoretical studies were carried out using the basic provisions of higher mathematics and theoretical mechanics. Experimental studies were conducted in laboratory and field conditions in accordance with proven techniques and were based on the theory of planning a multifactorial experiment. As a result of laboratory studies at the angles of installation of the cob separating device from 25° to 30° and the speed of the stretching rollers 905–1006–1 min damage to the ears is 0.05–0.10%. According to the data of field experimental studies, the optimal geometric parameters and kinematic modes of operation of the combine for harvesting sugar corn are obtained: the angle of inclination of the feed chains ‘legs to the longitudinal axis of the chain contour is 90°; the rotation frequency of the stretching rollers is 971 min–1; the speed of the combine movement is 4 km/h. With this combination of geometric parameters and kinematic modes of damage to the cob is 0.15%.