The Qaidam Basin is well known by its rich mineral and water resources,many rivers originate from the northern slope of the east Kunlun Mountains,and these rivers are the important water supply sources of the Saline Lake and irreplaceable water resources for the local industrial and agricultural development. For the worry about water security,the isotopic characteristics of river water from the northern slope of the east Kunlun Mountains were concluded and compared with those in the 1980s,and the change of streamflow in the Qaidam Basin in recent more than 20 years was analyzed. Precipitation,glacier-snow melt water and air humidity were increased,and a local climate change was resulted in under human activities,such as the construction of reservoirs and irrigation systems. Global warming was the main factor causing these changes and increasing runoff volume of the rivers and water level of the lakes. Analyzed from the change of runoff volume of the rivers only,the water recharge in the Qaidam Basin will be increased in the future,which is very beneficial for exploiting mineral resources in the Qaidam Basin. However,the impact of construction and maintenance of reservoirs and the exploitation of salt lake resources should be considered and paid enough attention to.