In order to reduce the potatoes drop damage in the process of sorting and explore the separator working conditions than can influence the potato drop damage, this paper took 'Helan15' as the experimental material, using the conveying speed, excluding force, the drop height and the moisture content of potato separator as the test factors, and potato drop damage level as the response value, Quadratic regression orthogonal rotation test was carried out. The malformed variance analysis of the test results was conducted by Design-Expert 8.0.6 software. The influence of each experimental factor on the damage level of potato drop was explored by response surface, and the optimal working parameters of potato sorter were determined. The results of the drop test showed that the order of the degree of influence on the damage level of potato drop was water content, drop height, conveying speed, and removal force. When the conveying speed was 0.3 m/s, the removing force was 15 N, the falling height was 45 cm, and the water content was 75.36%, the sorting machine had the lowest drop damage grade on potatoes. The actual drop damage grade of potatoes was 0.84, which fitted well with the predicted value.