There are appreciable losses in crop output at all the stages in grain production like harvesting, transportation, storage, etc. To reduce grain loss during the harvesting process, it is desirable to effectively control the header height of the combine harvester. The desired header height control is able to follow the shape of the terrain and reject disturbances from the ground. This paper presents an optimal state feedback LQR controller to achieve the control objectives. By properly defining the states and choosing the cost function, the full state feedback controller is shown to accomplish the control goals. Then a reduced states feedback controller, which uses a skyhook damper in the controller, is used to simplify the full state feedback controller. Simulation results show that with less feedback information, the reduced order state feedback controller preserves the ability to achieve good reference tracking and disturbance rejection.