Aiming at the shortage of potato combine harvesters and the poor passability of caterpillar chassis in hilly and mountainous areas, a self-propelled potato harvester with chassis walking device and multistage conveying and separating device was designed, and the passability of chassis and harvestability were analyzed theoretically. Firstly, the performance of harvester chassis driving on slope and obstacle crossing was analyzed theoretically, and the critical parameters of chassis passing were obtained. Secondly, the kinematic analysis of potato during harvest was carried out, and the relevant parameters of key working parts were obtained. At the same time, RecurDyn simulation software was used to simulate the multi-body dynamics of the whole machine, and the relevant motion parameters of the self-propelled potato combine suitable for the horizontal and longitudinal slopes in hilly areas, across trenches and straight walls were obtained. The simulation results showed that the maximum climbing angle of longitudinal slope driving was 28°, the maximum slope angle of transverse slope driving was 20°, the maximum height of the machine crossing vertical obstacles was 150mm, and the maximum crossing trench width was 300mm. The results showed that the rate of damaged potato and the rate of broken potato were 1.92% and 2.86%, respectively, which met the standard of damaged potato and broken potato less than 2% and 3%, respectively. The harvester can meet the longitudinal slope of 25° and drive steadily, cross the trench of 300mm width and climb over the straight wall of 150mm, which was consistent with the simulation results, and verified the accuracy of the simulation. This study can meet the design requirements of crawler potato harvester driving performance, and provide theoretical basis and reference for the design of crawler root harvester in hilly and mountainous areas.