Aiming at the problems of high potato damage rate, low soil removal rate, single structure and inconvenient adjustment of the separation device of the traditional potato harvester, a left and right spiral symmetrical soil removal roller and adjustable type made of polyurethane material were designed. The smooth rollers were alternately arranged and combined in the potato harvester roller group conveying and separating device. Through the dynamic analysis of the machine body structure, the coupling mechanism analysis of potato-soil separation and the discrete analysis of the collision between potatoes in the soil removal process, the key factors affecting the potato damage rate and soil removal rate of the roller-type conveying and separating device of the potato harvester were determined. And it was tested, taking the potato damage rate and soil removal rate as the test index, taking the distance between the soil removal roller and the smooth roller, the rotation speed and the inclination angle of the conveying separation device as the experimental factors, a mathematical regression model was established for the orthogonal test results, and a response surface analysis was carried out. Through analysis and parametric analysis, it was determined that when the distance between the soil removal roller and the smooth roller was 16.5mm, the speed of the soil removal roller was 100r/min, the speed of the smooth roller was 100r/min, and the inclination angle of the separation device was 8°, the damage potato rate was 0.64%, and soil removal rate was 97.1%. Compared with the traditional potato harvester separation device, the potato damage rate was decreased by 0.12 percentage points, and the soil removal rate was increased by 2.6 percentage points. The device can meet the requirements of conveying separation.