As the important breakthrough in geothermal exploration in Southern Tibet in recent years, the Gudui (Gobdu) high- temperature geothermal system has attracted widespread attention for its typical characteristics of shallow burial, high temperature, high lithium content and intense activity. The boiling springs and hot springs in the Gudui geothermal system are mainly Na- Cl type, the warm springs and cold springs are mainly Na- Cl- HCO3, Na- HCO3- Cl and Na- HCO3 types, and the surface water mainly belong to Ca- Mg- SO4- HCO3 and Na- Ca- Mg- SO4- Cl- HCO3 types; these differences may reflect their different origins and material sources. The comprehensive analysis of Na- K, quartz, K- Mg geothermometer indicate that the reservoir temperature was up to 240. 56℃. Except for four samples, the results of Na- K geothermometer is always higher than the quartz and K- Mg geothermometers. Most geothermal water samples collected from Gudui are far from the full equilibrium line in Na- K- Mg ternary diagram, suggesting that the complete chemical re- equilibrium has not been achieved as these geothermal waters flow upward from reservoirs towards spring vents and possibly mix with cooler waters. Geochemical characteristics analysis indicates that Cl, Na, K, SiO2, B, As, Li, Rb, Cs and F are the characteristic components of Gudui geothermal waters. The good linear relations between Cl and other characteristic constituents reflect the existence of a parent geothermal liquid (PGL) below Gudui. Comprehensive comparative analysis of the chloride- enthalpy diagram suggests that there may be two kinds parent geothermal liquid below Gudui that have Cl - concentration, enthalpy value and their corresponding temperature are 567 mg/L, 1562. 5 J/g, 335. 5℃ and 697 mg/L, 1250 J/g, 282. 5℃. The PGL ascends to the surface through different channels and may cool by conduction of heat to reservoir host rocks, by boiling, or by mixing with cooler groundwater. This study is of great significance to deeply understand the hydrochemical characteristics and formation process of high- temperature lithium- rich geothermal system in southern Tibet, and has important practical significance for the rational utilization of clean geothermal energy and geothermal- type lithium resources in southern Tibet in the future.