Abstract: Continuous mixer is an important part of variable rate fertilizer applicator. The mixing process of fertilizer particle is an important factor for the precision ratio of various fertilizer compositions. To investigate the mixing characteristic of particles， the discrete element model was adopted to track the movement of each fertilizer particle. The mathematical model was established based on Hertz theory and Newtons second law. Variation coefficients were taken as mixing index to analyze the degree of mixing. The internal structure of mixing device and the speed of spindle were put emphasis upon to discuss the mixing characteristics of fertilizer particle. It is found that with the increase of the number of spreading plate and blocking material barrel， the fertilizer particle tended to uniform mixing. With the increase of spindle speed， the fertilizer particle mixing uniformity was improved obviously. The simulation results provided a reference for the design of mixing device.

Key words: discrete element model, continuous mixer, numerical simulation