In order to solve the problem of the poor fluidity of ginseng seeds caused seed-metering device the serious shortage of filling-seed and the easy damage of seeds. The method of enlarging seeds disturbance and reducing local seeds friction was adopted to improve the filling-seed performance of seed-metering device. And based on this a precision special-hole type seed-metering device with convex hull was designed. Through the analysis of the force and motion state of seeds in the filling-seed area, the mechanism of convex hull and special-hole improving filling-seed performance of seed-metering device was expounded. And through the calculation of the kinematic analysis of theoretical calculation to filling-seed process, the single factor simulation test was conducted through the EDEM, the influence of different structural parameters on seeds was analyzed and the structural parameters of special-hole were ascertained. Then the quadratic regression orthogonal rotation combination test was done, with the rotation rate of special-hole, height diameter ratio of convex hull and seed’s height as the test factors, and the qualified index, the multiple index and the missing index as the test index. Experimental results showed that the primary and secondary order of influencing conformity index was height diameter ratio of convex hull, the rotation rate of special-hole and seed’s height. When the rotation rate of special-hole was 29.75r/min, height diameter ratio of convex hull was 0.43 and seed’s height was 53.92mm, filling-seed performance was the optimum, the qualified index was 95.59%, the multiple index was 2.97% and the missing index was 1.40%. The bench test and field experiment were conducted to testify the working performance of seed-metering device, which showed that the precision special-hole type seed-metering device with convex hull had the filling-seed better performance and can meet the requirements of ginseng sow.