Abstract: Geothermal resources are very rich in Beijing with a long development history and many user companies. In order to scientifically and rationally evaluate geothermal resources, the actual exploitation and utilization and the influence of recharge are fully considered. Based on the detailed survey data and the long series of monitoring data of the Xiaotangshan geothermal field, tracer tests are used to calculate the resources of a typical geothermal heating project in the Xiaotangshan area, and the available resources are estimated as 340 m³/h under the current temperature kept for 100 years. At the same time, the long-term dynamic monitoring data are used to analyze the whole thermal field in the Xiaotangshan area. The results show that the average annual net production is correlated with the average annual groundwater level decrease, and the geothermal resources are 365.1×10⁴ m³ while the annual groundwater level decline is controlled at 2.0 m. Combined with the development and utilization data and experience of the Xiaotangshan geothermal field for many years, it is considered that the reasonable and scientific development and utilization of geothermal resources must adhere to the mode of “fixed mining by heat and irrigated mining”.