This paper describes a gas turbine inlet air cooling system using high pressure spray nozzle. Thermal characteristics and fluid properties were studied by performing the wind tunnel test that simulated an actual gas turbine intake cooling duct part. A result of examining the cooling performance due to differences in the inlet relative humidity 30~50%RH, the cooling performance was the same. Furthermore, as a result of investigating the cooling performance due to the difference in a spray nozzle number, in one case, it became clear from 33°C that it is possible for 28°C to cool ,and in three case, it became clear from 33°C that it is possible for 23°C to cool. The air humidifying cooling process of an actual gas turbine inlet duct part was clarified.