Abstract: Abstract: Potato has become the important food and cash crop. In recent years, potato planting areas have increased gradually in China, reaching more than 8 million hm2 in 2013. Southwestern mountainous area, Inner Mongolia, northwest of China and northeast of China are the main producing areas of potato. The potato planting area in southwestern mountainous area accounts for about a third of the national total area. Because of the characteristics of the terrain in this area, potato grows mainly in hills and mountains. So only small harvest machines can be used to harvest potatoes. So many potato planting areas result in the higher requirements to the harvest performance of potato harvester. According to the characteristics of potato planting in China, the most ways of harvesting potato are two-stage harvesting, so the digging model of potato harvester is common in the domestic potato harvest process and is used in most areas in China. In order to solve the potato mechanization harvesting problem in plots of hilly mountain or other small plots and small breeding field, in view of the key factors affecting the potato harvest in the areas of hill and mountain, like small plots of land, large slope, rocks, we researched and designed the 4U1Z type of potato digger to solve the related problems. This article described the main structure and working principle of the machine and structure design of key parts. Analysis of kinematics on the digging shovel and vibrating screen mechanism was carried out. The three-dimensional model of the complete machine was established by Solidworks. In Adams/View environment simulation analysis was carried out for the digging shovel and vibrating screen mechanism. We also obtained the relevant images of the kinematics parameters. The theory analysis was combined with simulation analysis method to determine the stability of the machine. Orthogonal test was carried out for the digging shovel and vibrating screen mechanism. The influence factors of field experiment included forward speed, inclination angle of the vibrating screen and vibrational frequency (speed of tractor pto shaft). Evaluation indices included obvious rate of potato and reliability, injury rate of potato. Using the Design-Expert software, the influencing parameters of harvest performance were analyzed, and the optimized parameters were obtained and verified by comparison with national industry standard. Results indicated that: vibration in the opposite directions offset some of the inertial force, improving the stability of the machine. The test results showed that when forward speed was 0.8 m/s, inclination angle of vibrating screen was 5o, and frequency of vibrating screen was 10 times per second, the obvious rate of potato was 94.89%, the reliability was 93.41%, injury rate of potato was 1.22%, and the effect of digging operation was the best. The research provided a solution of the potato digger to high breakdown rate and difficult mechanized harvesting caused by the terrain characteristics such as small plots of land, large slope and rocks in southwestern mountainous area. Promoting potato industry in the areas of hilly mountain has become large-scale and standardized. It is helpful for farmers to solve problems caused by without proper harvesting machine in the process of the harvest and promote the development of potato production mechanization in China.