Taking the vertical sand-roller rice milling machine as an example, this paper carries out the simulation calculation of the materials’ movements inside the whitening chamber based on the discrete element method via the analysis software EDEM. The study sets up the discrete model of the whitening chamber and the brown rice with corresponding parameters and performs the discrete element simulation on material flows inside the whitening chamber; for the convenience of the analysis, the data of the motion locus curve and the force on the brown rice during the whitening process are presented with charts. These simulation results would provide references for the study of the generating mechanism of broken rice.