Operating speed control system and method for combine harvester

The invention discloses an operating speed control system and method for a combine harvester. The system comprises a computing unit, a measurement and control box, a motor driver and a sensor group, wherein, the computing unit processes the received data and sending out a control instruction which takes the expected operating speed as a target; the measurement and control box collects the data acquired by the sensor group, transfers the data to the computing unit, converts the control instruction of the computing unit into a pulse control signal and then outputs the signal to the motor driver; the motor driver receives the pulse control signal and controls an actuating mechanism to work according to the control instruction; and the sensor group acquires the torque and revolving speed of a threshing cylinder, the revolving speed and operating speed of an engine, and the stroke of a variable speed oil cylinder. By utilizing the system, the optimum operating speed of the combine harvester can be determined so as