In view of the complex structure and poor performance of the existing rice fertilizer discharging device, the centrifugal cone-disc fertilizer discharging device with a two-way screw fertilizer feeding was designed. The device is mainly composed of fertilizer box, two-way screw, centrifugal cone-disc fertilizer device and other components. The fertilizer in the fertilizer box is conveyed to the centrifugal cone-disc fertilizer discharging device by a two-way spiral during working, and then is evenly dispersed and discharged along the inner wall of the cone under the centrifugal force of the centrifugal cone. The key structural parameters of the fertilizer discharging device are identified as the two-way spiral outer diameter of 100 mm, the inner diameter of 40 mm, the pitch of 90 mm, the thread thickness of 3 mm, the minimum radius of the centrifugal cone of 60 mm, and the inclination angle of the centrifugal cone of 45°. The three dimensional and quadratic general rotation combination tests were conduct used two-way spiral speed, the speed of the centrifugal cone, and the travel speed of the fertilizer discharging device as the test factors, and the coefficient of variation of the discharging uniformity as the evaluation index. The results show that the significance of the influence of various factors on the coefficient of variation of fertilizer uniformity is in the descending order of the two-way spiral speed, the centrifugal cone speed, and the travel speed of the fertilizer discharging device. After optimization, the minimum value of the coefficient of variation of fertilizer uniformity is 17.60% under the optimization condition with the bidirectional spiral of 5.27 r/min, the centrifugal cone of 243.7 r/min, the device travel speed of 0.66 m/s. The average value of the coefficient of variation of fertilizer uniformity is 17.16% in the verification test. It is found that the optimized numerical solution is in good agreement with the results of the verification test.