in order to improve the adaptability of maize harvester to different plant distances, reduce the rate of missed harvest and improve the working efficiency, this paper designed a new plant distance measuring device for maize harvester with adjustable plant spacing, which greatly improved the operating precision and efficiency of maize harvester. Device with single chip microcomputer as the control center, pressure sensor for measuring the force component, stepper motor as the power source, planting distance is obtained by measurement of photoelectric encoder, is converted to A digital signal by A/D converter, again by single-chip computer for processing, to implement the instructions issued at the end, adjust the corn harvester the spacing of the removable ear device, so as to realize the different planting distance of corn harvesting operations, for the research of corn harvest machinery automation provides A valuable reference.