This paper reveals the temporal and spatial variations of stable isotope in precipita-tion of the Yarlung Zangbo River Basin based on the variations of δ¹⁸O in precipitation at four stations (Lhaze, Nugesha, Yangcun and Nuxia) in 2005. The results show that δ¹⁸O of pre-cipitation has distinct seasonal changes in the Yarlung Zangbo River Basin. The higher value of δ¹⁸O occurs in spring prior to monsoon precipitation, and the lower value occurs during monsoon precipitation. From the spatial variations, with the altitude-effect and rainout process during moisture transport along the Yarlung Zangbo River Valley, 18O of precipitation is gradually depleted. Thus, δ¹⁸O of precipitation decreases gradually from the downstream to the upstream, and the lapse rate of δ¹⁸O in precipitation is approximately 0.34‰/100m and 0.7‰/100km for the two reasons. During monsoon precipitation, spatial variation of δ¹⁸O in precipitation is dominated by the amount effect in the large scale synoptic condition.