[Objective] The research aimed to analyze the formation reason of groundwater hydrochemical characteristics in the dry valley area of Wadi Bay of Libya and provide the scientific basis for the reasonable development utilization and the environmental protection of groundwater.[Method] Took Wadi Bay area（dry valley）of Libya as the example,Piper trilinear graphic representation method,the descriptive statistics,the ion ratio coefficient method and the isotope evidence were used to systematically study the special hydrochemical characteristics of shallow groundwater in the arid climate condition in Wadi Bay area of Libya.[Result] The salt content of groundwater in the area was very high,and TDS was during 3.2-8.4 g/L.The main groundwater type was Cl·SO4-Na·Ca,then was Cl·SO4-Na·Ca·Mg.The concentrations of Cl-,Na＋ and SO2-4,etc.in the groundwater in 70 km from the sea had the remarkable variation,but the concentrations of Mn2＋,Ba2＋,Si2＋,NH＋4 and NO-3 didn＇t have the same variation phenomenon.[Conclusion] The hydrochemical characteristics of shallow groundwater didn＇t relate to the dissolution infiltration reaction,the evaporation concentration effect and human activities.The major cause was the mixing effect of salt and fresh water in the invasion process of seawater.
