To gain an in-depth understanding of hydrological cycle processes in alpine and arid watersheds and provide scientific guidance for local water resources management and utilization, a study was conducted on the monthly variation characteristics of stable hydrogen and oxygen isotopes and Cl^- concentrations in the Golmud River. Water recharge sources were identified, water recharge contributions were quantitatively assessed using the MixSIAR model, and evaporation degrees were evaluated through the Rayleigh fractionation model. The results reveal that river water in July has exhibited significantly higher δ 2H and δ 18O values with lower Cl^- concentration compared to other months; the δ 2H and δ 18O values are the lowest in Xiaonanchuan but higher in Yeniugou across different months and gradually increase along river flow from Nachitai, while Cl^- concentration gradually increases from Xiaonanchuan at the lowest value to the east branch at the highest value; the δ 2H- δ 18O relationship point falls lower right below the local meteoric water line with the minimum lc-excess of -19.03‰. The mean water recharge elevation exceeds 4 700 m. Glacier meltwater and groundwater are primary recharge sources of river water, with an increasing precipitation contribution in July. There is a 9% evaporation loss on average along the river, peaking at ＞25% in the downstream east branch. These results demonstrate strong agreements between the variations of lc-excess and Cl^- concentration, validating the effectiveness of the evaporation evaluation method.