To study the effects of the forward speed of tractor and the hydraulic control system on the sowing depth, the experiment was carried out in a soil bin. In this paper, comparison experiments were implemented between hydraulic system and spring adjustment system with the traveling speeds of 3km/h, 4km/h, 5km/h, soil compaction of 273.8kPa、473.7kPa、730.1kPa and the sowing depth of 5.1 cm respectively. The sowing depth variation coefficient of hydraulic system were respectively 9.38%, 11.28% and 12.71%, and the traditional spring system were respectively 11.99%, 12.90%, 15.38% at the working speeds of 3 km/h, 4 km/h, 5 km/h. And when the average soil compaction was 273.8 kPa, 473.7 kPa and 730.1 kPa, the sowing depth variation coefficient of hydraulic system were respectively 9.20%, 11.28%, 12.04% and the traditional spring system were respectively 11.05%, 12.90%, 13.96%. The results showed that the hydraulic system had better performance in terms of depth consistency and qualification index of seeding depth than conventional spring adjustment. Moreover, as the tractor's travel speed increases and the soil compaction, its sowing depth variation coefficient showed a upward trend and sowing depth consistency showed a downward trend.
