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Aiming at the practical problems of large soil clods, uneven surface and uneven mixing of straw and soil in seed bed after operation in autumn, 1ZLZ-300 fullwidth compound seed bed preparation machine with the function of seed bed land leveling and straw stubble combing was designed. According to the technical requirements of spring land preparation and the characteristics of viscous soil, the overall design scheme of seed bed land preparation machine was determined. The self-excited soil horizontal shear unit and the elastic carding unit were studied respectively. By means of EDEM discrete element simulation technology, a simulation model of straw mixed buried soil in northeast black soil area was established based on field measurement data and related literature. The working mechanism of each embedded component and its effect on soil disturbance were obtained through the simulation of the operation process of seed bed preparation machine. The Box - Behnken orthogonal test was carried out with the depth of the shovel, the depth of the spring tooth and the angle of the spring tooth as the test factors, and the straw coverage rate of the surface and the surface flatness of the soil as the evaluation indexes. The optimum working parameters of 1ZLZ-300 fullwidth compound seed bed preparation machine at the working speed of 10 km/h were determined to be the depth of 10.0 cm, the depth of 8.0 cm and the angle of 0 ° of the spring teeth. Under the above conditions, the average straw coverage rate was 50.7%, the average surface flatness of the soil was 3.2 cm, the average soil compactness of 0~10 cm depth seed bed was 73.3 kPa, the average soil compactness of 10~20 cm depth seed bed was 690.2 kPa, the average soil breaking rate was 89.7%. The test results showed that all the performance indexes of the machine met the technical requirements of spring land preparation in overlying tillage. The development of1ZLZ-300 full width compound seed bed preparation machine provided the equipment support for the popularization of black soil conservation tillage corn straw mulching and mixed returning technology in central and eastern Jilin Province.