Numerical simulation of heating process of different materials under microwave irradiation has been widely studied. This study reviews the model development of microwave heating under different application scenarios in recent years, new CFD models for microwave-assisted gasification of biomass are also introduced. The results show that more accurate simulation results can be obtained by properly adjusting the improved model according to the different situations. When the structure of the object in the microwave field is relatively simple, one-dimensional or two-dimensional processing can be used in the model construction to simplify the calculation. When there is phase change during the microwave heating process, it is more helpful to improve the corresponding mass transfer model and consider the volume change to obtain accurate simulation results. When the heated object is moving, choosing appropriate boundary conditions can simplify the calculation and improve the accuracy of simulation results. The contents detailed in this review not only introduce the model development of microwave heating, but also present the simulation results of microwave-assisted gasification of biomass. (C) 2020 Published by Elsevier Ltd.