Radiation would be more important in turbine heat transfer due to higher temperature and multicomposition gas conditions in the future. The main goal of the current study is analyzing the characteristics of conjugate heat transfer considering radiation heat transfer, multicomposition gas, either with or without TBC coated. Both experimental and numerical studies were carried out. By comparing the experimental and the numerical results, it was concluded that the implemented thermal conduction/convection/radiation simulation method is valid for the cases studied. The results have shown that higher percentage of steam in the gas composition leads to higher temperature (lower normalized temperature) on the plate. With the percentage of steam in the hot gas increasing per 7%, the normalized temperature on the plate decreases about 0.02. The heat insulation effect of TBC is more obvious when the radiation effects are strong.