This chapter explores the applicationApplications of the DEMDiscrete Element Method (DEM) to model key phenomena in conventional fluidized beds. It reviews DEM’s role in simulating the hydrodynamics of various reactor configurations, including bubbling, spouted and circulating fluidized bedsCirculating Fluidized Bed (CFB). The critical processes such as particle mixing and segregationMixing and segregation in fluidized beds are then introduced. Furthermore, the chapter covers DEM-based studies on heat transferHeat transfer mechanismsMechanisms and the integration withChemical reactions chemical reactionReaction models to simulate reactive flows. By presenting core research focus and examples, this chapter underscores DEM’s unique capability to provide particle-scale insights that are crucial for advancing the fundamental understanding and optimizationOptimization of fluidized bed systems.