The invention relates to a control system and method for driving a threshing cylinder of a combine harvester, and belongs to the technical field of agricultural harvest machinery. The control system comprises a hydraulic part and an electric control part, wherein the hydraulic part comprises a hydraulic motor for driving the threshing cylinder, and a closed type speed regulation main working circuit composed of an electric-hydraulic proportional variable pump, the hydraulic motor is provided with parallel oil change control circuits, and the proportional variable pump is provided with a variable control circuit composed of a tandem proportional directional valve and a double-acting hydraulic variable cylinder; and the electric control part comprises a revolution speed transducer arranged on the threshing cylinder and a pressure transducer arranged on the main working circuit, signal output ends of the revolution speed transducer and the pressure transducer are connected with corresponding signal input ends of a PLC (programmable logic controller) respectively, and a control signal output end of the PLC is connected with a control signal input end of the variable control circuit after passing through an amplifying device. The invention solves the problem that parameters are difficult to detect, also avoids hysteresis quality, and can ensure that the threshing cylinder is always in a stable ideal working state.