Aiming at the problems of large machine and low cutting quality of potato seed potato cutting machine in China, a multi-functional small roller type potato seed potato grading and cutting machine was designed. The structural design of the whole machine and key components was carried out. Through theoretical analysis and numerical calculation, the main factors affecting the grading effect were determined to be the inclination angle of the roller group, the speed of the first row of roller group and the feeding amount. The main factors affecting the cutting effect were determined to be the vertical center distance of the clamping roller, the angle between the center line of the clamping roller and the horizontal direction and the speed of the clamping roller. Based on EDEM-RecurDyn coupling simulation and theoretical analysis, the range of rotation speed and feeding amount of a row of rollers was determined. The inclination angle, the rotation speed and feeding amount of rollers were taken as experimental factors, and the classification efficiency and classification accuracy were taken as evaluation indexes., Box-Behnken experimental design method was used to determine the optimal parameter combination of the feeding grading device. The inclination angle of the roller group was 10.53°, the rotation speed of the first row of roller groups was 88.7r/min, and the feeding amount was 52.22kg/min. At this time, the grading accuracy was 92.65%, and the grading efficiency was 52.04kg/min. The prototype test showed that under the optimal parameter combination, the grading accuracy was 91.67%, the grading efficiency was 49.44kg/min, the qualified rate of the cutting block was 95.75%, the cutting efficiency was 48.24kg/min, and the uniformity of the potato block was good, which met the agronomic requirements of the seed potato cutting block.