In order to explore the hydrochemical changes along the Golmud River, 33 groups of water samples were collected and tested in this area from July to August 2019. Piper triangle graphic method and Gibbs graphic method were adopted to analyze the hydrochemical characteristics, causes of formation and main ion sources of the Golmud River from source to inlet. The results show that the hydrochemistry along the Golmud River changes from the type of HCO₃-Cl-Na-Ca-Mg to the type of HCO₃-Cl-Na-Mg-Ca, with Cl^- and Na⁺ gradually dominating on the north side of overflow zone. The main causes of formation of hydrochemical types include lixiviation and evaporation concentration effect. Sources of ions are mainly from the weathering dissolution of halite, carbonate, sulfate and so on.