Abstract: The analysis of thermal-humid environment distribution of underground hydropower station is of great significance for plant operation. This paper, by using CFD considering outdoor weather, indoor heat and wet source, studies the distribution law of thermal-humid environment and through online and offline monitoring results of generator layer which shows simulation precision. The results of simulation is used to investigate the distribution of thermal-humid environment of the generator layer as well as the analysis of thermal comfort parameters of air distribution. Results show that the three kinds of meteorological parameters of thermal-humid environment under the condition of similar distribution, uniform temperature field distribution results in uneven temperature coefficient value, velocity field and humidity field changes obviously, so the speed of non-uniform coefficient is large, three weather conditions of energy utilization coefficient are large that reflects better energy saving potential.