Abstract: Abstract: The degree of automation of domestic combine harvester is low, and the operation is complex, it is difficult for workers to understand the actual adjustment of working parts. Crop height, crop length, height of the ground and the lack of consistency in course of project led to the continuous adjustment of harvester's joystick. The traditional operation method, in which experiences are excessively relied on, cannot meet the requirements of automatic operation of domestic-made combine harvester. The current operation method is an obstacle to the development of the automatic control of the combine harvester. In this paper, a device of adjusting combine harvester header parameters was designed. The header parameters include height of header, height of reel, position of reel and speed of reel. The control function of header parameters adjusting device is to adjust height of header, height of reel, position and speed of reel. The header parameter adjusting device was composed of sensor modules, PLC control units, display modules, key module, header drive parts module and so on. The sensor modules were used to detect the parameter of header which include height of header, height of reel, position of reel, speed of reel and forward speed. Sensor modules detect the signal inputed into PLC control unit. PLC control unit is the core component of the adjusting device. PLC performs data operation and processing. Using touch display screen as human-computer interaction tools, which communicates with PLC. The display interface includes parameters displaying and setting, and displayed parameters include header parameter, operating speed, crop height and so on. The key module adopts self-reset and self-locking switch to realize manual and automatic function signal input. At the same time, PLC receives the key information and make judgments, and then sends the control signal to drive header hydraulic system to carry out the movement of the mechanism. Header drive parts modules include lectromagnetic directional valve and proportional solenoid valve, which adopts the hydraulic control principle. High reel speed has a large impact on crop yield and increase grain losses. It is difficult to push crops to header and proceed to the next step of threshing, clearing and collection at low reel speed, and it is difficult to match the change of operation speed with the reel speed. In this paper, an automatic control method of reel speed was presented. By analyzing the working process of reel, a mathematical model of reel speed was established, and fuzzy PID algorithm is used to realize the automatic control of reel speed. The header parameter adjusting device was installed on the test prototype, and the regulatory tests, data records and data analysis were carried out. The test results showed that header height, reel height, reel position and reel speed could be electrically controlled by the header parameter adjusting device. Relative adjustment errors of header height, reel height, reel position and reel speed were 7.4%, 3.4%, 2.0% and 7.8% respectively. The operation speed of maximum relative error was 3.4%. The response time is less than 0.8 s, and the adjustment time is less than 1.7 s. The system was proved to meet the design requirements of header parameter controller of combine harvester. The research results can be applied in intelligent operation of combine harvester.