94.2%。Metering device capability directly influences the performance of rapeseed planter. In order to define the mechanical structure parameters and the movement of air current in the pneumatic precision metering device, simulation research was respectively made on air current under positive and negative pressure with orthogonal method and ANSYS/CFX tools, and the research result was also validated by the experiment. The research shows that the quantity of holes in metering device disc is the pivotal factor of influencing the air current and seeding quality. When the quantity of hole is 25 and the pressure of hole in negative pressing area is -754Pa, the seeding eligible index is 94.2%. 