Abstract: In order to study relationship between installation position of hydraulic cylinder and driving energy consumption in automatic unloading driving mechanism of silage harvester′s material box，automatic unloading driving mechanism for material box of ensilage ramie combine harvester was as research object.According to minimum energy consumption target，using method of motion dynamics to design and calculation parameters of overturning driving force of material box under given motion conditions，installation position of hydraulic cylinder on frame，installation height of hydraulic cylinder on material box，and maximum working stroke of the hydraulic cylinder.Changing trend of velocity and acceleration of piston rod articulation point was obtained under overturning operation stationarity of material box.Results showed that an isosceles triangular structure with bottom of hydraulic cylinder length and waist of length which from articulation joints of hydraulic cylinder to overturning center of material box could meet minimum requirement of energy consumption，and maximum speed and acceleration under given motion conditions were 0.088 m/s and 0.010 m/s2.This study could provide a theoretical basis for future related research.