Although China is the largest country of root and stem crops production, its mechanized production technology is very backward, and the specialization, high efficiency and serialization of the working machines are still lower, which lags behind developed countries. Aiming at the extrusive problems in the domestic harvester such as low level of mechanical automation, high labor intensity, lack of auto-follow row function, low obvious rate, high injury rate and high undug rate, taking 4UGS2 double row potato harvester as the carrier and the ridge section direction as the research object, comprehensively using mechanical, hydraulic and electronic control and other key technologies, the auto-follow row device was designed, which consisted of ridge profiling mechanism, traction mechanism, hydraulic system and electronic control system. The real-time adjustment algorithm of harvester operation route was introduced based on PID control technology, and the harvester operation route adjustment model was constructed. Finally, the optimal control of track of harvester was tested to verify the effectiveness of potato harvester, which included the installation of auto-follow row device and the non-installation of auto-follow row device. The auto-follow row device was used to harvest three ridges and then relying on the tractor driver to manually match the row to harvest three ridges. The experiment was carried out by interlacing with six ridges, and the harvester speed was 5.02km/h (i.e. 1.40m/s). The results showed that 4UGS2 harvester exhibited better adaptation on the moist land with soft soil and less hardening, and the auto-follow row device and other parts of the machine had good working performance. The obvious rate, injury rate, undug rate and other indicators reached or exceeded the qualification requirements. According to the experiment and statistics, in the three ridges with manually matching the row, the obvious rate was 95.09%, the injury rate was 2.84%, and the undug rate was 3.38%. Meanwhile, in the three ridges with auto-follow row device, the potato obvious rate, injury rate and undug rate were 97.25%, 1.44% and 1.57%, respectively. Through comparison, it can be seen that when the harvester was installed with the auto-follow row device, the obvious rate was increased by 2.16 percentage points, the injury rate was decreased by 1.40 percentage points, and the undug rate was decreased by 1.81 percentage points. Due to the installation of auto-follow row device, the harvester can automatically adjust the working posture according to the change of the ground ridge, carry on the positive excavation and realize the accurate control of the harvest operation. The potato obvious rate, injury rate and undug rate were improved simultaneously. Besides, the stability of the auto-follow row device would be affected if the ridge cross section size was changed greatly and individual collapse of the ridge occurred in the course of the test. The machine was characterized by its stable and reliable work, efficient operation and better performance index. The research can provide an effective reference for the development of intelligent harvesting technology for other root and stem crops harvesting machines.