A three-dimensional CFD (computational fluid dynamics) steady-state model was established to simulate biomass gasification in a circulating fluidized-bed (CFB) reactor. The standard k-epsilon turbulence model was coupled with the kinetic theory of granular flow to simulate the hydrodynamics in the gasifier. The kinetics of homogeneous and heterogeneous reactions were studied and integrated with the equations of continuity, motion, and energy to describe the distributions of velocity, temperature, and concentration. The simulation results were compared to experimental data. The impacts of turbulence models, radiation model, water gas shift (WGS) reaction, and equivalence ratio (ER) were investigated to present a reliable understanding of biomass gasification in a CFB reactor.