Abstract: The variations of stable oxgen isotopic in different water mediums are analyzed for the period of sampling using the data in precipitation,surface firn,glacier melt water and stream water sampling in Urumqi River basin.It reveals that there is marked temperature effect on stable oxygen isotope in precipitation,and the effect relates to the altitude.Fbwever,no marked altitude effect is found in the surface firn and the glacier melt water;the stable oxygen isotopic ratios in glacier melt water are all lower than those in stream water.Furthermore,the impact degree of different factors on the variations of stable oxygen isotope in the process of water cycle and their interaction are evaluated in the study,which pnwides an example for the application of stable isotopic technique to the study on water cycle.