| Northwestern Shandong Province is the richest geothermal resources area. The whole area is dominated by the low, medium temperature geothermal resources formed in the mechanism of heat flow by thermal conduction chiefly.Hydrogeochemical characteristics of geothermal water, water-rock interaction and the formation process of geothermal water in the study area were analysed and studyed, and hydrogeochemical characteristics was founded obviouly zonated:①For Yanggu - Qihe raised karst geothermal water, water - rock interaction has not yet reached the equilibrium state, but also in the "immature water" stage; with the dissolution of gypsum and rock salt as the main water-rock interaction, salinity of geothermal water gradually increased and water chemistry type is represented by SO4-Ca water and gradually evolved into Cl ? SO4-Na ? Ca water.②Jiyang - Linqing depression sandstone pores mostly in the local balance area, the water - rock interaction improved but not yet reached the equilibrium state; the principal water– rock interaction was salt dissolution and cation exchange adsorption, and salinity increased and water chemistry evolution was by Na-Cl primarily.Hydrogen and oxygen isotopic compositions of the study area's geothermal water were distributed nearby the global and local water line withδD value from -49.9‰to -90.67‰,andδ18O from-8.0‰to -10.6‰, indicating that geothermal water was from rainfall infiltration after a long distance heating,which was from the southeastern Taishan Mountains with 256m 441m high and the surrounding mountains. In addition, desulfurization coefficient and the Schoeller diagram of the underground water, also shown the main causes of atmospheric precipitation. According to d value ,the excess parameter of 2H,degree of mineralization and characteristic parameters ,the renewal ability of the underground water was evaluated .Based on comprehensive analysis and study on hydrodynamic field,hydro-temperature field and chemical field of geothermal water, this paper summarized formation conditions and hydro-geological conceptual model of geothermal water in the study area. According to the differences of hydrogeology condition including structural situation and hydrodynamic field and with or without mixing phenomena of cold and hot water , karst geothermal water flow system in the study area can be divided into recycling-based and closed geothermal water flow system.In the hot and cold water mixed better area, geothermal water had stronger renewal ability and better circle condition with low salinity (as the west section of Jinan north geothermal field representative) as main characteristics ,while in the hot and cold water mixed badly area, geothermal water had weaker renewal ability and worse circle condition ,with high salinity (as the east section of Jinan north geothermal field representative) as main characteristics . Without mixing phenomena of cold and hot water in geothermal field in east Liaocheng, geothermal water formed closed geothermal water flow system., where water-rock interaction was relatively high and 18O drifted significantly, updated capacity of geothermal water was poorer than that in north Jinan.Hydrodynamic environment of pore water in concave field was slowness flow zones of internal north china basin. Because geothermal water was preserved in anoxic and closed hydrogeochemical environment and hydrochemistry type of geothermal water tended to be uniform by Na-Cl primarily in long geological evolutionary history, the renewal ability of geothermal water was weak.. For trap geothermal water of fault concentrated belt on the marginal parts of the depression, salinity, main components and trace element increased obviously, because one part of trap geothermal water was sedimentary genesis, which was from the center of the basin and in the same horizon as the geothermal reservoir or deep formation , and the renewal ability of geothermal water was correspondingly weak.
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