Based on observed precipitation δ¹?O data from 1992 to 2005 together with simulation results from two isotope-enabled models, this study investigates the factors controlling interannual variability in precipitation δ¹?O at Delingha and its relationship with moisture transport. Multi-scale correlations between precipitation δ¹?O and temperature, spatial correlations with moisture flux fields, and backward trajectory analyses of moisture sources were conducted. The results show that precipitation δ¹?O exhibits a pronounced temperature effect for the complete dataset and at the monthly scale (r > 0.7, p < 0.001), whereas its interannual variability is not controlled by temperature (r < 0, p > 0.05). Instead, interannual δ¹?O variability is primarily governed by moisture transport. Compared with δ¹?O-depleted years, δ¹?O-enriched years are characterized by significantly enhanced transport of marine moisture from the southeast. These results indicate that moisture source and transport processes exert a stronger control on interannual δ¹?O variability than temperature. The findings advance our understanding of isotopic effects and moisture transport processes on the northeastern Tibetan Plateau, thereby improving the reliability of regional paleoclimate reconstructions.