A method for evaluating the influence of different transport properties of different combustion gas components on convective heat transfer was proposed in this paper. Based on the proposed method, four commonly approaches for calculating molecular viscosity coefficient and thermal conductivity were selected to investigate the effect of different combinations of the approaches on convective heat transfer. The results show when the inlet temperatures are 1000K and 2200K, the local Nusselt number of the flat plate increases from 2.7% to 4.0%, and when the inlet temperatures are1000K and 1500K, the local Nusselt number of turbine cascade increases from 4.58% to 9.70%, respectively.