The chemical and isotopic compositions of Jiangxi Province thermal waters are considered. It is shown, carbon dioxide thermal waters are more mineralized (TDS=0.3-3.9 g/l) than nitric thermal waters (TDS= 0.3-0.4 g/l), in addition, the carbon dioxide thermal waters, in general, are weak acid and neutral (pH= 5.70-7.77), the nitric thermal waters - alkaline (pH= 8.5-9.25). It should be noted, the content of Na⁺, Si, HCO₃^-, CO₃^2-, sometimes SO₄^2- Ca²⁺ and K⁺ is predominant in the carbon dioxide thermal waters, the content of Na⁺, Si, F^-, HCO₃^- is predominant, but concentrations of Ca²⁺, Mg²⁺, Cl^- are quite low in the nitric thermal waters. It has been identified that the Jiangxi Province thermal waters have meteoric origin. It has been established, the main factor responsible for low concentrations of some chemical elements and high content of others is equilibrium-nonequilibrium state of water-rock system, which can be determined by continuous dissolution of aluminosilicate minerals and simultaneous precipitation of secondary minerals.