Aiming at the problems that current domestic corn headers continued to be mechanically adjusted and the adjustment was inconvenient, an automatic control system for corn header height was designed. The automatic control system included a floating compression profiling mechanism, STM32 control unit, display screen, key switch, solenoid valve drive module, etc. Floating compression profiling mechanism was composed of angle sensor, profiling plate, torsion spring, fixed shaft, etc. The profiling plate and angle sensor were designed and selected, and the analysis on working process and force of the profiling plate were carried out. ADAMS software was utilized to obtain the vertical height change of the profiling plate under different torque conditions of the torsion spring, and the torsion spring was designed according to the simulation results to achieve better adhesion to the ground. The automatic adjustment parameter model of the header height was established, and PID control algorithm was used to realize the automatic adjustment of the header height. The simulation model was built in Matlab/Simulink software and the system simulation was performed. After tune calculation optimization, when Kp was 1.2, Ki was 0.68 and Kd was 0.9, PID controller could meet the design requirements of the automatic control system of the header height. In automatic profiling mode, the control system detected the height of the header from the ground through the profiling mechanism, and the header cylinder automatically adjusted the height of the header from the ground after processing by the STM32 control unit. In manual mode, STM32 control unit recognized the key signal and controlled the lifting of the header according to different key signals. After completing the design of the automatic control system for the header height, the control system was installed on the 4YZP4HQ corn harvester, and functional tests were carried out. In the manual mode, the adjustment time was taken as the system response index, and a stopwatch was used to record the time required for the header to move from the start to the specified position, and the results showed that the average response speed during adjustment was 0.42m/s. In automatic profiling mode, the control system automatically adjusted the header height from the ground, the height of the header was measured randomly when the harvester stopped every 20~30m, and the result showed that the error between the actual height of the header and the set height was within 20mm. The average speed of the header in manual mode and the actual height in automatic control mode met the needs of the corn harvester header control. The research result could provide reference for the intelligent research of corn harvester.