Abstract: To solve the problem cassava harvesters, 4 UMG-140 poking roller type cassava 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 are introduced, and its key components including digging device, poking roller device and depth device are discussed and analyzed. The combine harvester can complete root digging and separating from soil, root conveying and lifting and root lying on land in one operation. The harvester realizes efficient harvesting with tractor wheels running in furrows between ridges in harvesting without rolling on and damaging cassava roots, which is convenient for tractor driver’s operation. Field experiments showed that 4 UMG-140 poking roller type cassava harvester could meet with the mechanical harvesting requirements of cassava planted with wide-and-narrow-double-row ridge planting model. With obvious cassava rate 95.2%, loss rate7.6% and productivity 0.35 hm2/h, the harvester could satisfy the design requirements.