The computational fluid dynamics（CFD ）numerical model is established to analyze the aerodynamic heating of gap for thermal protection system. The heat flux distribution of gap is compared with that of plate. Maximum heat flux appear at the upper of gap，and the heat flux on windward side is greater than that on leeward side. The heat flux is concentrated in upper gap that is approximately equal to the width of gap. The FEM heat transfer model for heat control analysis of gap is established based on the heat flux of gap. The aerodynamic heating and cavity radiation of gap result in the increase of temperature of structure，which is the reason of the short circuit phenomenon of gap. Finally，the influences of gap shape on the heat control performance are studied. As the width of gap increases，maximum temperature of structure increases. As the radius of rounded corner increases，maximum temperature of structure decreases. As the height of gap step increases，maximum temperature of structure increases，when the height of windward side is greater than that of leeward side. However maximum temperature of structure decreases when the height of windward side is less than that of leeward side.