A three-dimensional unsteady-state CFD (computational fluid dynamics) model is built to simulate biomass gasification in a circulating fluidized bed. The RNG (renormalization group) k-epsilon turbulence model is coupled with the enhanced wall treatment to describe the hydrodynamic regime of the gas-particle system. The conservation of momentum, mass, and energy equations are integrated with reaction kinetics to simulate chemical reactions in the gasifier. The impact of product distribution coefficient, theta, for char combustion on the CFD biomass gasification model is examined in nine cases. According to the simulation results, the coefficient of theta has a minor effect on the predictions of outlet gas compositions. However, it is found that the value of theta can influence the profile of gasifier temperature, and the peak temperature regions from the cases assigning 0.50 to the coefficient appear faster than those from the models using higher values of theta.