The studies of chemical compositions of modern hot spring water and gases, isotopic compositions of H 2 O, He, Ar, CH 4 , CO 2 in northwest Hunan show that the chemical characteristics of spring water are markedly different, which indicates the difference of background value of country rocks and the difference of the effect of water-rock reaction. The geothermal systems in the studied regions are middle-high temperature geothermal systems. The distributions of springs are controlled by the press and press-shear faults that do not dissect deeply to the mantle. The hot spring water is of meteoric water. The origin of materials in the hot springs is correlated with the sedimentary rocks.