Heat transfer behaviors in a pulsed fluidized bed are numerically investigated by means of a combined approach of computational fluid dynamics (CFD) and discrete element method (DEM). The effect of pulsation flow on bed heat transfer characteristics is evaluated. It is found that the pulsed gas flow leads to an intense oscillating flow behavior in the bed, enhancing the the cooling rate of hot particles. Three kinds of heat transfer mechanisms arc examined. The results reveal that the particle-fluid convection is dominated. Meanwhile, heat transfer mechanisms in a polydisperse system are also discussed. It is observed that the addition of fine particles promotes the total particle-fluid convection and the fluctuating degree with time becomes evident. (C) 2020 Elsevier B.V. All rights reserved.