Abstract: According to geological structure, hydrogeochemical and isotope characteristics of Gushi depression, the hydrodynamic conditions of geothermal water were discussed. The results show that from the west to the east the deeper the faults cut, the longer the retention time of geothermal water becomes. Water alternation changes fast then exceptionally slowly. Water-rock interaction changes insufficiently then intensely, and occurrence environment becomes more and more enclosed. In the west of Gushi depression(Fuping and Sanyuan counties), faults cut shallowly and water retention time is short, when water alternation of local precipitation is active and interaction between water and rocks is not sufficient as well as the geothermal water is mixed with modern circulated water and occurrence environment becomes open, the renewable ability become stronger. Therefore its current exploitation yield can be maintained. In the east of Gushi depression(Weinan and Huayin counties), the faults cut the deep basement and geothermal water retention time becomes longer, and water-rock interaction becomes intense. Water alternation conditions are unusually slow and its occurrence environment becomes enclosed. Because of weak renewable ability,its exploitation yield should be controlled.