Heihe is a relative larger inland river of Northwest China.It spans three major land form types of mountain,basin and desert areas.The water resources are extremely deficient.The water problem is outstanding,especially in the contradiction between economic construction and ecological environment.This paper,based on the investigation of the hydrologic characteristics in the Heihe watershed,focuses on studies of the chemical properties of the water there.A large sec-tion of the Heihe are dominated with HCO 3- in anion and Ca 2+ in cation,with orders in milligram equivalent percentage of HCO 3ˉ >Clˉ>SO 42+ in anion and Ca 2+ >Mg 2+ >Na + +K + in cation.However,different orders occur at the hydrologic station of Zhengyixia,namely,HCO 3ˉ >SO 42- >Cl ˉ in anion and Na + +K + >Mg 2+ >Ca 2+ in cation.According to conventional hydro-geological methods,three types of river water can be classified by taking the major aqueous anions and cations milligram equi-valents as criteria,i.e.,bicarbonate,sulfate and chloride.Tests show that most of the samples belong to bicarbonate types.According to the sampling test,the total mineralization of river water varies between365～751mg /l,total hardness varies between3.93～10.46me /l,and total alkality,between3.17～7.30me /l.This paper also analyses the trace element of river water in the Heihe and makes an assess-ment of the water quality of the region and policy implications to water conservation are presen-ted.