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Aiming at the problems of no-till corn planter, such as difficulty of passing through stubble fields, mixing of grass and soil in the seeding strip and the poor operation quality, a grass-soil separation device with combination of stubble cutting and grass guiding was designed based on the technical idea of combined operation of driving stubble cutting and passive guide grass. Several functions were achieved using the device, including cutting, poking, throwing, guiding, separation and flowing of both straw and grass. Based on the theoretical analysis of the interaction law between the key components (e.g., concave notched disc cutter and guide grass board) and straw and grass, key influencing factors and their value ranges were investigated. The optimal parameters of the guide board were determined by using CFD simulation software. To determine the optimal combination of structural parameters of concave notched disc cutter, the interaction model of grass-soil separation device-soil-straw was established by using EDEM discrete element simulation technology. The results showed that the main structural parameters affecting the tool performance were embedded depth, the height of cutter tooth and the angle of blade. When the embedded depth, blade height and knife dish angle were 73.63mm, 69.70mm and 23.41°, respectively, the performance of the device was the best, as indicated by good passage of the device with seeding straw cleaning rate of 90.16% and soil disturbance of 20.85%, which could meet the agronomic and technical requirements of no-till corn planter. Moreover, the device working performance was stable. 