A variable control system was designed and manufactured using eccentric orifice wheeled metering device for 2BYD–6 type rape shallow tillage fertilizing joint type sowing machine. The control system consists of an emission-detection system which depends on a pressure sensor directly detecting changes in quality seed box to realize the detection seed quantity sowed and a an two parts, displacement and displacement detection system regulation system components, displacement detection system by means of a pressure sensor directly detect changes in quality seed box to achieve the amount of canola seed testing Eemission-control system which based on electrical signals converted from the detection result of the detection system is converted to an electrical signal, to achieve emissions regulatedion and the desired amount of seed by controlling the motor speed of seeding shaft driven by the SCM seeding shaft drive motor speed to achieve the desired amount of seed. Bench test shows that the control system can accurately detect the amount of seed sowed per time unit which compared to the theoretical value, and realize variable seeding by regulating the rotational speed of metering device. The accumulation error for detecting rape seed volume per minute can be controlled below 3.5%, with seeding uniformity coefficient of variation less than 7%.