The temperature and thickness of the room temperature zone are the important indicators of the shallow geothermal field. In engineering practice, the temperature of the room temperature zone is commonly used as the original temperature of the underground rock and soil. It shows that the temperature of the room temperature zone is closely related to the annual average air temperature and the terrestrial heat flow density. The shallow geothermal energy is generated under the combined effect of the solar radiation heat and the terrestrial heat flow, and it belongs to the low-temperature geothermal energy occurring in the soils, sandstones, groundwater within a few hundred meters of near-surface. According to temperature characteristics of the room temperature zone, China shallow geothermal energy is divided into three types（tH≥15 ℃, tH =10-15 ℃ and tH≤ 10 ℃）.
