According to the statistics of gold mines in South Africa, from 1956 ~ 196 1 year, the death rate of heatstroke among thousands of workers working at the wet bulb temperature of 32.8 ~ 33.8℃ is 0.57. The climatic conditions that affect human thermal balance are temperature, humidity and wind speed. Many countries have done a lot of research on microclimate suitable for working environment. In addition to the dry-bulb temperature and wet-bulb temperature adopted earlier, there are various indicators, such as wet and dry katabatic degree (cooling degree), equivalent temperature, actual temperature, thermal index and so on. In order to accurately reflect the suitable temperature and humidity of labor, a comprehensive index is put forward. China's mines still take the dry bulb temperature as the index, and stipulate that the temperature of underground workers' workplaces should not exceed 26℃.