The rape rotary tillage combined transplanter takes the tractor as power. As the PTO of tractor is fixed value, the planting speed of rape combined transplanter cannot change with the forward speed of tractor, which leads to the instability of the planting hole distance. A hole distance control system was designed, which was based on STM32 controller. The forward speed of tractor was detected by a ground wheel speed encoder. The speed of the hydraulic drive motor was adjusted by the electric proportional hydraulic system in real time. Generally, the real time matching of planting speed and forward speed was realized. The bench test of hole distance control system was developed. The test result showed that the hydraulic motor speed was consistent with the change trend of ground wheel speed, and the delay time was within 600ms. Moreover, the hydraulic drive motor of the left and right two transplanting units had excellent synchronization, and the average speed error was 0.7%. The electrohydraulic control system of hole distance was installed on the rape combined transplanter. Comparative field tests were conducted for four theoretical hole distances (150mm,160mm,170mm,180mm) and four operating speeds (2km/h, 3km/h, 4km/h and 5km/h). The test result indicated that the transplanter had terrific hole distance stability. The primary and secondary factors affecting the consistency coefficient of variation were theoretical hole distance and forward speed. Theoretical hole distance had the most significant effect on the consistency of hole distance. When the hole distance was 160mm, the consistency coefficient of variation of hole distance at different forward speed can keep a small value, which indicated that the hole distance of 160mm was the most ideal hole distance. 