Abstract: The heat transfer process of the Lamilly was analyzed, and the formulas for describing the thermal radiation inside the Lamilloy were provided under the suppose of configuration simplifying, for example, the complex surface cutting off and the infinity plate supposition. The thermal radiation and convection heat transfer in interior cooling passage of the Lamilloy with a typical configuration was studied by the method of three dimensional fluid-solid coupled computation. The ratio of thermal radiative to convective heat flux θ was introduced and it was a function of the cooling air inlet Re number and the gas heating power. Analysis was carried out under 4 typical aero-engine working conditions, and correction was performed with exponential fit. A simple method was put forth to evaluate the effect of thermal radiation, and with this method, the importance of thermal radiation could be easily assessed.