Based on a solid fuel scramjet experiment date, A CFD software is used in the numerical simulation respectively about scramjet combustor of the initial condition and the burning flow after the launch. Given the import boundary of PMMA fuel according to user defined function way. Numerical simulation results indicate that the flow field characteristics in combustor accord with theoretical analysis; it has certain different about the fuel regression rate on the surface of the solid fuel in combustor compare with experimental measurement, but the whole burning face’s distribution curve of fuel regression rate along the axial is approximate with the experimental value; The pressure distribution near fuel surface along the axial is satisfying agreement with the experimental data. The results of the study show that the numerical model established is reasonable and have some reference value for the theory research of solid fuel scramjet.