The Qingtu lake is a closed and terminal lake in the inland river of the monsoon border area,where are the ideal areas for studying of the paleoclimate and the paleoenvironment because of its ecological vulnerability and climate sensitivity. Precipitation is an important input factor for the ecosystem in the arid area. So it is of great theoretical and practical significance to study the characteristics of hydrogen and oxygen isotopes and the source of water vapor for the management of water resources in Qingtu Lake under the background of global climate change. The precipitation deltaD and delta~(18)O data in the period from May to October in 2017 were analyzed to examine the relationship between the characteristics of deltaD and delta~(18)O their environmental factors. Furthermore,the air mass transmission pathway was determined and regional water vapor sources were identified based on HYSPLIT model. The meteoric water line equation is; the average deltaD value is - 36.82,ranging from - 118.36 to ~ 15.63,and the average delta~(18)O value is - 5.36,ranging from - 16.97 to 3.23. The average excess deuterium(d - excess) value is 6.03,ranging from - 23.64 to - 21.93,which is less than the global average 10. Aprecipitation effectexists significantly whereas thetemperature effectis not obvious. There are obvious seasonal changes of deltaD and delta~(18)O in atmospheric precipitation in Qingtu lake. Influenced by westerly vapor,local evaporation and Asian monsoon,the water vapor source of the precipitation in the Qingtu lake is obviously seasonal. In summer,it mainly comes from westerly circulation,southeast monsoon and local evaporation, and in autumn it comes from the polar continental air mass of Siberia and Mongolia. The artificial seasonal evaporation of lake water formed by ecological replenishment has become one of the sources of summer precipitation and water vapor,which is of great significance for improving the ecological environment of the lake area.