Surface ablation and in-depth temperature distribution of the charring material are the key properties of the thermal protection system in re-entry vehicles subjected to aerodynamic heating. To investigate the factors affecting the ablation performance of charring materials, the influence of decomposition reaction and surface recession on ablation was added to the heat conduction and surface energy balance equation, to comprehend the phenomenon of surface material removal. The model developed in this study was verified by comparing with results from traditional finite difference method. Furthermore, the effects of external constant heat flux, initial material thickness, and heating time on ablation were determined and discussed on temperature, surface recession, and density distribution. The change trend of the external heat flux significantly affects the change trend of the surface temperature. The material thickness and heating time have great influence on the bottom temperature. This paper contributes to the understanding of the heat transfer and ablation of the charring materials, thereby providing a basis for the selection of the thermal protection material for re-entry vehicles.