The invention discloses a low-loss potato harvesting machine. According to the invention, the rear end of a potato combine harvester system support is provided with a baffle plate type potato elevating conveyor belt; a potato vehicle-loading height adjusting hydraulic cylinder and a vehicle-loading elevating conveyor telescopic hydraulic cylinder are arranged on the baffle plate type potato elevating conveyor belt which is connected with a grille potato-soil separation device; a grill potato-soil separation device driving motor is arranged on the grille potato-soil separation device; a tractortraction device is used for connection of a tractor; and the front end of the potato combine harvester system support is provided with a digging shovel; the baffle plate type potato elevating conveyor belt is connected with a baffle plate type potato elevating conveyor belt driving motor; and the bottom part of the potato combine harvester system support is provided with land wheels. The low-losspotato harvesting machine provided by the invention has the following beneficial effects: combined operation of potato-soil separation, conveying, concentrated collection and the like is realized; the efficiency of harvesting is high; and damage is insusceptible to occurring in the harvesting process of potatoes.