A comprehensive 2-D numerical model has been developed to simulate the coal gasification and investigate the effect of reactor height on the coal gasification in fluidized bed. Gas-solidflow, homogeneous and heterogeneous chemical reactions were considered. An Eulerian model for fluid phase and discrete particle method (Lagrangian) for particle phase were used in this study. The reaction rates of homogeneous and heterogeneous reactions were determined by Arrhenius-eddy dissipation reaction rate and Arrhenius-diffusion rate, respectively. Simulations were performed in a fluidized bed coal gasifier with twelve different reactor heights and with a diameter of 0.22 m. The calculated values were compared with the experimental values for the reactor height of 2 m available in open literature. It shows that the predicted exit gas mole fractions are in a good agreement with the experimental data.