Abstract: With the large-scale mining of geothermal water, it has made great influence on the chemical observation of underground water. This paper aims at preliminary discussion on the mechanism from two aspects, which may cause the influence: underground hydrodynamic condition and thermal-dynamical condition. On the initial period of mining, it was not obvious. The longer the mining continues, the more obvious the influence will cause. The underground water's pressure and temperature plays a dominant role on that variation process, so it is crucial to monitor well's situation on the water's chemical observation.

Key words: Water chemistry observation, Anomaly variation mechanism, Structure background, Wang3 well