Abstract: Abstract: In order to solve the inadaptation problems of unsuitability to small plots for present side output-type and container-type potato combine harvesters, and time-consuming, tedious, and inefficient process in manual picking up of potatoes for traditional potato diggers, a new type midsize potato combine harvester was developed with semi-mounted on a 44-58.8 kW tractor. It consists of profiling soil-breaking device, excavating mechanism, soil-potato separating and conveying equipment, stalk separating device, potato transport, grading, collecting, and bagging devices, driven system, hydraulic control device, rack and wheel, etc. The working width is 1 400 mm, and the working productivity is 0.3-0.5 hm2/h. The potato harvester enables a one-stop achievement of potato digging, soil-potato separating, stalk removing, potato conveying, grading, collecting, and bagging procedures. It effectively decreases the labor cost, simplifies the commodity potato processing links, and enhances the production efficiency. The designed split-type and three-order plane digging shovel improves the ability of burying and breaking soil. The digging depth can be adjusted by the profiling soil-breaking roll, which reduces the vertical load of rack. The profiling soil-breaking device and the excavation equipment assembly are connected with the rack through the parallel four-bar mechanism, and their movements are controlled by tractor hydraulic output, which can keep the potato harvester longitudinally at level status and keep the digging shovel with same burying performance in different digging depth. The stalk separation device has a compact structure and good working reliability. The harvest tests on the four types of potato planting fields, as mulching and bed planting irrigable land, fully-mulching and bed planting dry land, parallel sowing dry land, and bed planting dry land, were conducted. The results show that the developed harvester exhibits better performances and adaptation on the dry land potato harvest, especially for fully-mulching dry land. It shows excellent performances for soil-potato separation, also stalk and mulch separation. The productivity achieves 0.4 hm2/h. The loss rate, potato damage rate, and impurity rate are less than 1.38%, 4.2%, and 3.42%, respectively. However, the harvester gives the relatively poor harvest performance and adaptation on the bed planting irrigable land, and displays the high impurity rate.