Abstract: Abstract：Tianjin, one of the four municipalities directly under the Central Government, has relatively high temperature field background. The exploitation of geothermal resources in this city has a long history and has been conducted on large scales, and the development momentum of the reinjection recycling exploitation is promising. The monitoring data on the steady flow temperatures of the continuously explored well head demonstrate that the geothermal fluid temperature of each reservoir has not changed obviously along with the long-term exploitation. The results of the same well temperature testing during the reinjection period and the non-reinjection period show that, when the lower temperature original fluid is reinjected, the temperature of different depths is dropped by 0.1~0.76 ℃/a, but the temperature of the main exploitation section goes up again month by month during the non-reinjection period. The reservoir temperature of the reinjection well rises again quickly and gradually reaches the same level of the same period last year before the coming reinjection period.