The invention relates to the technical field of agricultural machinery, in particular to a rheum officinale digging harvester and a digging harvest method thereof. The rheum officinale digging harvester comprises a rack, a stalk cutting mechanism, a stalk pulling mechanism, a first collecting box, a double-rod hydraulic drive, a digging and cutting assembly, a conveying mechanism, a second collecting box and a water tank; the stalk cutting mechanism and the stalk pulling mechanism are installed at the front portion of the rack, the first collecting box, the double-rod hydraulic drive and the water tank are installed in the middle of the rack, and a conveying belt I for conveying rheum officinale stalks is arranged between a stalk lifting mechanism and the first collecting box; the double-rod hydraulic drive comprises an oil pump and double oil cylinders in output connection with the oil pump, each oil cylinder is provided with an oil cylinder push rod, the oil cylinder push rod locatedat the front portion of the rack is connected to the digging and cutting assembly, and the second collecting box includes an outer box and a cleaning box located in the outer box. By means of the rheum officinale digging harvester, the mechanized harvest of rheum officinale is achieved, the harvesting efficiency is improved, and the harvester is reasonable, simple and compact in mechanical structure, convenient to manufacture and flexible and convenient to control and operate.