Abstract: In order to improve the current situation of low efficiency of potato mechanical harvesting in hilly and mountainous areas of China, this paper focused on the study of three key mechanisms for a potato harvester:an innovative three-wheel mechanism, which replaced traditional wheels as the front wheel of the harvester to enable movement in mountainous terrain; a digging shovel mechanism,which was designed to improve the digging depth; and a grading mechanism, in which the steepest descent line was used instead of an inclined straight line to arrange the grading rollers, aiming to enhance grading efficiency and accuracy. After completing the design, EDEM discrete element simulation software was used to simulate both the inclined straight-line type and brachistochrone-type grading devices.The results showed that the steepest descent classification effect was better. ABAQUS finite element software was used to verify the structural strength of key components, and the results indicated that the strength met the design requirements. The purpose of this design is to promote the mechanical harvesting technology in mountainous areas typical of Guizhou terraces and improve the efficiency of crop grading.