Abstract: Mechanization level of potato planting determines the increase of potato production. However, the potato planting areas mostly distribute in the hilly and mountainous regions in the southwest China. Planting mode varies with the diverse landforms, such as lateral and vertical slopes, in small agricultural machinery, even artificially planted, particularly on the scattered plots in irregular shape. The imported potato planters have shown a high level of intelligence and precision, due to the use of some advanced technologies, such as automatic control, hydraulic system for seed supply, seeding electronic monitoring. In most planters, the sowing depth of seeding monomer can be adjusted according to the profile of monomer in large multi-row (more than 4 lines). Unfortunately, the large-scale adjustment of the sowing depth during seeding cannot be suitable for small plots and the hilly mountainous areas of China. Since small-scale potato planters suitable for hilly mountain areas mainly depend on the overall profile of ground wheel, the application of seeding monomer profile is also lacking, as well the consistency of sowing depth. Therefore, the level of mechanization for potato planting is posing a great challenge on the yield of potatoes in hilly areas. In this study, a new type of control device for sowing depth was designed in potato planter, where the structure parameters of key components include the length of profiling mechanism, traction angle, lateral width, and spring stiffness, together with the configuration of profiling wheel, and the structure of opener. The theoretical structural parameters of the device were also determined to examine the consistency of sowing depth in potato planters. A stability model of trenching depth was used to establish the motion law of profiling unit in potato planter. In the field test, the key factors were obtained for the stability of trenching depth. Test factors can be selected including the initial traction angle, spring stiffness and machine operating speed. The qualification index and variation coefficient of ditch depth were chosen as test evaluation indexes. The combination of quadratic orthogonal rotation was used to test the level range of influence factors for the stability of the sowing depth. An optimization has been performed on the effects of various factors on the ditch consistency of the uniform test device. The optimized motion parameters in the device were obtained to meet the consistency of the sowing depth. The optimum operation parameters in potato sowing can be achieved, where the ditch depth qualification index is 96.6% and the ditch depth variation coefficient is 8.9%, when the working speed is 1 m/s, the initial traction angle is 0°, and the spring stiffness is 10 N/mm. These findings can provide a new design reference to regulate the sowing depth of planters in potato seedlings.