Abstract: To solve the problem of high requirement of extensive manual operations facing cassava stage-harvesting, a 4UMZ-1400 rearcollected type cassava combined harvester was designed according to agronomic requirements of cassava wide-and-narrow-double-row ridge planting model. In this paper, working principle and gross structure of the designed harvester were introduced, and its key components including vibration digging device, cassava root and soil separation device and cassava root collection device were discussed and analyzed. The combine harvester completed root digging and separating from soil, root conveying and lifting, root collecting,packing, automatically discharging and loading onto trucks in one operation. The harvester realized efficient harvesting with tractor wheels running in furrows between ridges in harvesting without rolling on and damaging cassava roots, which was convenient for tractor driver’s operation. The application of combined operation avoided manual collection of cassava roots and effectively improved harvest efficiency. Field experiments showed the harvester met the mechanical harvesting requirements of cassava planted with wide-and-narrowdouble-row ridge planting model. With a loss rate of ≤6.8%, impurity rate of ≤9.7%, and productivity of 0.21-0.33 hm~2/h, the harvester satisfied the design requirements.