To overcome the limitations of traditional investigations on the temporal-spatial distributions of precipitation isotopic compositions based on single-source data in the Qaidam Basin, this study synthesized data from multiple sources, including TNIP, previous literatures, C-Isoscape, and GCMs, to establish the local meteoric water line (LMWL) and analyze intra-annual and interannual variations of precipitation isotopic compositions as well as temperature and precipitation quantity effects. The findings indicated that the slope and interception of the LMWL were lower than those of the Global Meteoric Water Line (GMWL), with the slope showing a gradual rising eastward spatially, attributed to the difference in below-cloud secondary evaporation. On intra-annual scale, precipitation δ 18O shows a seasonal variation with high values in summer and low values in winter, in which trend over time is influenced by temperature fluctuations. A significant temperature effect was observed for precipitation isotopes across the basin, whereas no obvious precipitation quantity effect was identified.