With the aim to solve the problems of the soil blocking, the high rate of tuber damage, and the bad adaptability to different heights of ridge, MZPH-820 potato harvester was designed. The blades of the digging device were designed separating from each other, as well as their supported pipes. The guide rollers of the screening conveyor belt installed on two cantilever plates individually, this brought the transverse through shaft a bit large displacement to the upwards. Both of them made the blades and the soil-cutting discs be the only two kinds of soil-engaging parts, and effectively prevented vines winding and soil blocking. The blades angle adjusting mechanism performed the angle adjustment of the blades and the guide rollers of the screening conveyor belt in the same time, and the adjusting range of the blades angle is 18°～30°. Through adjusting the heights of mound drum and rear wheels harmoniously, the harvester could meet the working demand of various ridge height in range of 100～400mm and ensure the presetting angle of the blades. This improved greatly the adaptability to different ridge heights. Field experimental results show that in conditions of high ridge wide row, MZPH-820 potato harvester performed smoothly in digging, lifting and transporting without any blocking, and potatoes were separated effectively from soil. Its productivity was 0.10hm2/h, damage rate was 0.3%, and losing rate was 3.9%, all meeting the technical requirements.