Abstract: In view of the difficulty of measuring the parameters of the discrete element particle model of organic fertilizers, especially powdered organic fertilizers, the particle diameter of organic fertilizers was calibrated using image processing methods.A regression model was established through simulation experiments and the angle of repose was used as the target value.The rolling friction coefficient of fertilizer and the rolling friction coefficient of organic fertilizer-steel plate were analyzed by variance analysis.Finally, through actual test comparison, the rolling friction coefficient of granular organic fertilizer-organic fertilizer was determined to be 0.10, the rolling friction coefficient of organic fertilizer-steel plate was 0.30; powder organic fertilizer-organic fertilizer.The coefficient of rolling friction is 0.40, and the coefficient of rolling friction of organic fertilizer-steel is 0.30.The results show that the relative error between the simulated angle of repose and the actual angle of repose of the granular organic fertilizer is 4.1%, and the relative error between the simulated angle of repose and the actual angle of repose of the powder organic fertilizer is 3.2%,and there is no significant difference, indicating that the discrete element parameters of the organic fertilizer are accurate.