Abstract: In order to study the influence of humid air on the cooling performance of turbine blade and build the cooling performance prediction model of humid air turbine, the experimental platform of normal pressure turbine blade cooling was established, and the experimental study of humid air as coolant medium was carried out. Under the condition of humid air moisture content of 15-80g/kg and temperature of 200℃, the impingement cooling of blade leading edge, the U-channel cooling of fin disturbing flow and the pin-fin cooling of blade trailing edge were experimentally studied. The variation of heat transfer performance of the target wall with moisture content and temperature under different Reynolds numbers was explored. The results indicate that the heat transfer intensity of the target wall increases with the increasing coolant humid ratio, the decreasing coolant temperature and the increasing coolant Reynolds number. When using the humid air with moisture content of 180g/kg, the area-averaged Nussult number of target wall for impingement cooling, U-channel cooling and pin-fin cooling increases by 6.5%, 10.0% and 9.2% respectively, compared with the case using dry air.