Fractal pore models, gas molecular movement models, and reaction models are combined to simulate char oxidation in char pores. The numerical results show the relationship between the pore structure and the apparent char reaction parameters. A modulus number phi is introduced to characterize the diffusion properties in fractal porous media with a relationship given for the apparent reaction parameter in terms of phi. The results show that the char combustion process is strongly impacted by the pore structure, and that the fractal dimension is an important parameter that should be considered in char combustion. Comparison with experimental data shows that this model is more accurate than the classical intrinsic combustion model.