Based on the obtained equations of motion, the models and optimal control algorithm for the hitching system of cotton harvesting machine (CHM) MX-1.8 are developed in the paper. The necessary conditions for optimal control of the CHM MX-1.8 motion are investigated using the Mayer problem and applying the Pontryagin maximum principle. The operation parameters of the CHM MX-1.8 hitching system under vertical vibrations are determined. The optimal angle of rotation of the rockshaft which predetermines the uniform oscillation of the picking unit of the harvester hitching system is determined.