Abstract: This paper reviews the recent advances in multi-scale computational fluid dynamics (CFD) simulations of biomass pyrolysis in fluidized bed reactors. The interconnection among molecular-scale, particle-scale, CFD cell-scale, and reactor-scale are first introduced, together with the Eulerian-Lagrangian (E-L) and Eulerian multi-fluid model (MFM) frameworks. Then an overview of the theoretical basis and practical applications of four main particle-scale models, i.e, uniform conversion model, progressive conversion model, interface-based model, and corrected uniform conversion model, are highlighted. The coupling of particle-scale models with CFD cell-scale models is discussed, as well as with molecular-scale models. Finally, the perspective of future work to develop reliable and efficient CFD models for simulating biomass pyrolysis in fluidized bed reactors is outlined.