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In consideration of the fact that the high rate of damage and bruising of potatoes is the bottleneck of potato harvest mechanization process, the potato’s damage and bruising mechanism, mainly including the impact and collision between potatoes and soil buffer production of potatoes, is not clear. Therefore, it is difficult to combine high efficiency separation with low loss harvesting, resulting in large economic losses, which limits the development of highperformance potato harvester. In the present work, the damage mechanism of potatoes was studied as key point, and the high efficiency, damage reduction and loss prevention in the potato harvesting process were taken as the research objectives. Under the condition of adapting to the planting pattern and agronomic characteristics in the north of China, the separation form of wavy separating sieve was proposed, and the separation mechanism of clods crushing and mechanical characteristics of potatoes on wavy separating sieve were clarified based on the discrete element method (DEM). It was found that the large inclination angle of wavy separating sieve was suitable for the small difference of wavy separating sieve running speed. Simultaneously, combined with the actual working condition of vibration separation, the separation form of damage control device of vibration and wavy separating sieve of potato harvester was optimized. It was demonstrated that the number of cresttrough on the wavy separating sieve in the second half of the separation sieve was two, that was, two wave crest and two wave trough. As a result, under the condition of the same separation distance stroke, when the wave screen surface inclination angle was large, it was suitable for the smaller separation screen operation speed. When the inclination angle on wavy separating sieve was 35°, the separation sieve running speed was 1.0m/s, the damage and bruising rate of potatoes were 1.31% and 1.44%, respectively. When inclination angle on wavy separating sieve was 15° and the separation sieve running speed was 2.0m/s, the damage and bruising rate of potatoes were 1.46% and 1.67%, respectively. It was noteworthy that the performance indexes of the damage control device of vibration and wavy separating sieve of potato harvester met the relevant standards.