Abstract: Abstract: As the parameters of discrete element model for organic fertilizer are difficult to obtain directly from literatures or experiments, this study proposed a method to calibrate the parameters based on tests of the angle of repose. Firstly, a physical test was carried out. The diameters of organic fertilizer particles were between 0.25 and 2 mm, the fertilizer moisture was 13.7%, and the organic fertilizer was crushed to meet the requirements of uniformity of fertilization. In the test, in order to obtain the organic fertilizer heap, the cylinder was lifted up by a universal testing instrument at a speed of 20 mm/s. Then, the angle of repose of the fertilizer was measured with inclinometer and the test was repeated for 10 times, as the mean angle of repose was 38.15°. Secondly, the simulation test was carried out. Considering the cohesion characteristics between particles of organic fertilizer, the contact model of Hertz-Mindlin with Johnson-Kendall-Roberts was used in simulation modeling. Since the organic fertilizer particles were near-spherical, the basic model of the software default was adopted to simulate organic fertilizer granules. In the simulation test, the relative error was 2.22% by comparing the angle of repose formed by a variety of particle sizes according to actual particle size distribution and the angle of repose formed by the same particle size (1 mm). Therefore, a basic sphere model with a radius of 1 mm was used and the three-dimension geometry model built by SolidWorks was imported into the simulation software, with the cylinder lifting speed was 20 mm/s, the total number of particles was 10 000, the generation rate was 2 000/s, the fixed time step was 22% of Rayleigh time step, the target save interval was 0.01 s, and the cell size was 2 mm. Not all discrete element model parameters of organic fertilizer had significant impact on the angle of repose, so a screening through Plackett-Burman Design was made. The results showed that rolling friction coefficient between organic fertilizer, surface energy (JKR) and rolling friction coefficient between organic fertilizer and steel plate had significant impact on angle of repose. The optimal value interval of the there significant parameters was determined by the steepest ascent test, and built the linear regression model of angle of repose through Central Composite Design. The fitting of the linear regression model was optimized by adding the quadratic term and cubic term of rolling friction coefficient between organic fertilizer with the fitting of the regression model had a great improvement, and the P value of the lack of fit was improved from 0.091 to 0.405 6. Thirdly, the optimal value of the significant parameters was obtained with the actual angle of repose as a goal, with the rolling friction coefficient between organic fertilizer was 0.10, the JKR was 0.015, and the rolling friction coefficient between organic fertilizer and steel plate was 0.11. Finally, in order to verify the accuracy of the calibrated parameters, the simulation verification test of the calibration parameters was carried out, and the relative error between the simulated angle of repose and the actual angle of repose is 0.42%, which meant that the calibration parameters were accurate. This study can provide reference for the selection of discrete element model parameters of organic fertilizer.