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The grain moisture content is high when corn is harvested in North China, and there is a problem of high broken rate of grain when using nail-toothed and pole-toothed threshing elements. In order to reduce the rate of broken grain during the threshing process, a rasp bar threshing element was designed. The influence of the forward inclination angle of the rasp bar on the force of the ear was analyzed and the top arc shape of the rasp bar was designed based on the size of the compression when the grain was broken. Based on EDEM the primary and secondary relationship between the rasp bar top parameters and the force of the ears was researched, and the four-factor four-level orthogonal test was designed by using the quasi-level method. The results showed that the better parameter combination of the rasp bar was forward: inclination angle was 75°, top rib inclination was 25°, top rib width was 6mm, and top rib height was 10mm. Through the bench test, the law of influence of the working parameters such as the rotor speed and the cylinder-concave clearance on the threshing effect of the drum was explored, it was found that when the moisture content of maize was 28.5%, the rotor speed was 300r/min, the cylinder concave clearance was 50mm, at that time, the rates of broken grains was 5.34%. Comparing the threshing effect of different threshing elements under the optimal working parameters, it was found that the rates of broken grains were decreased from 9.91% of the pole-toothed element and 7.83% of the pin-toothed element to 5.34% of the rasp-bar element. It was proved that the rasp bar threshing element can effectively reduce the rates of broken grains.