Aiming at the lack of entrainment loss detection technology in the current domestic corn kernel direct harvester kernel loss detection system, a corn kernel direct harvester entrainment loss detection system based on an embedded single-chip microcomputer was designed. The detection system included a loss detection sensor, a data collector and a data display terminal, which can monitor the cleaning loss and entrainment loss of the harvester at the same time, and feedback the harvesting loss rate and loss amount of the harvester in real time. The finite element analysis of monitoring boards of different materials and thicknesses was carried out through modal simulation software, and a 0.5mm thick 304 stainless steel plate was selected as the monitoring board;domestic EDA software was used to design signal processing circuits, including voltage followers and Butterworth filters, Multisim was used to simulate and analyze the performance of circuit;an adaptive time-limited filtering algorithm was designed based on the STM32 series single-chip microcomputer, which can effectively suppress the aftershock interference caused by the impact of grains and improve the accuracy of the sensor. On the test bench, under different conditions, the calibration test was carried out on corn kernels, residues and corn ears of different sizes to obtain signal characteristics;the installation test showed that the maximum error of the detection result of corn kernel entrainment loss was 9.96%, and the average error was about 6.52%, and the loss rate change trend feedback was timely, which can assist the staff in making operation decisions.