The tail area of the Shule River is an ecological security barrier to protect Dunhuang Oasis and culture,but there is relatively little research on hydrochemical chemistry.Based on field investigation and sampling test,the hydrochemical characteristics and Genetic Mechanism of groundwater in the tail area of the Shule River were confirmed through the methods of mathematical statistics,Piper trigram,ion correlation analysis,Gibbs diagram,and ion proportion coefficient.The results show that the groundwater quality in the tail area of the Shule River is weakly alkaline,with high total dissolved solids and high hardness,and the main hydrochemical type is Cl-·SO2-4-Na+.The hydrochemical evolution of groundwater is dominated by evaporation concentration,accompanied by weathering dissolution and cation exchange.Ca2+ and Mg2+ in groundwater are mainly derived from the dissolution of evaporite and silicate, and Na+ is dominated sourced from the dissolution of rock salt.The formation of high fluoride water is related to the widespread biotite minerals in gneiss,hydrogeochemical action dominated by evaporation and concentration, and low-lying topographic conditions.This research not only enrich the study of hydrochemical in the Shule River Basin,but also provide scientific basis for the protection and construction of the ecological security barrier of Dunhuang Oasis.