Abstract: Uniform fluctuation is required for the precision operation in the double-gear fertilizer. In this study, the staggered-gear fertilizer device was designed to improve the slicing and isometric displacement of straight tooth fat discharge gears. It was composed mainly of the left-handed fat wheel, right-handed fat wheel, shell, and transmission gear. The two rows of fat wheels were rotated inward to better mesh the fixed transmission gear. The fertilizer was driven to rotate in the box, and then flew down to the drain outlet along the volume space that formed by the ridge and the cogging. Thus the fertilizer discharge was realized after running. Parametric modeling and volume identification were utilized to determine the volume of wheel tooth fertilizer. The optimal amount of fertilizer discharge was determined by theoretical analysis. EDEM was used to simulate the fertilizer discharge, where the number of misaligned gear pieces and the clearance of two rows of fat wheels were used as test factors, while the uniformity of fertilizer discharge flow was used as the test index. Univariate pilot studies were also conducted after the single-factor test. Design-Expert 8.0.6 software was used to select the L₉(3⁴) orthogonal table for the data processing and statistical analysis in the orthogonal simulation test. ANOVA and range analysis were carried out after the test. The experimental results showed that significant correlations were found in the number of pieces in the discharging wheel (P=0.001<0.01) and the clearance of two staggered gears (0.01<P=0.0102<0.05) on the coefficient of variation of uniformity. The influencing factors on the test index were the number of wrong gear pieces and the clearance of the fat discharge wheel. Furthermore, the coefficient of variation was 4.69% for the fertilizer discharge flow, when the number of staggered-gear pieces and the clearance of the fertilizer discharge wheel were 3 pieces and 5 mm, respectively. The bench and comparative tests were also performed on the double- and staggered-gear fertilizer device after prototype manufacturing using 3D printing. The results show that the coefficient of variation was 4.74% for the fertilizer discharge flow of the staggered-gear device at a speed of 60 r/min, which was basically consistent with the theoretical one. The coefficient of variation was reduced by 10.68 percentage points for the double-gear discharge. The uniformity of fertilizer particles was effectively improved to fully meet the design requirements. At the same time, Origin software was used to linearly fit the speed of the gear device after bench tests. The fitting function equation was y=5.26x+45.03 with the coefficient of determination R²=0.99. The fertilization controller was designed after the bench test, according to the measured speed and flow curve of the fertilizer device. There was only a 3.1% average deviation of the fertilizer discharge flow rate in the fertilizer device that was controlled by the electronic control system, compared with the preset value. The electronic control system can be expected to improve the particle's uniformity via the precise control of speed and fertilizer discharge. In summary, the fertilizer device with the optimized parameters performed precise and uniform fertilizer discharge. The finding can also provide a strong reference for the design and optimization of the precision control fertilizer device.