The Bowen ratio (β) is an important parameter for characterizing land surface processes, reflecting the energy balance and partitioning among soil, vegetation and the atmosphere, and it is a hotspot in the research on the biogeophysical effects of vegetation changes. In this study, the Qinghai-Tibetan plateau was chosen as the study area, utilizing evapotranspiration data obtained from the global-scale ARTS (air-relative-humidity-based two-source) remote sensing evapotranspiration model and albedo data derived from GLASS, we determined the annual mean β values spanning 2000 to 2018. Using random forests, structural equation modelling and multivariate linear regression methods, we combined the climatic factors (annual total precipitation(MAP), mean annual temperature(MAT), mean annual albedo (MAA)) and vegetation factors (mean annual Normalized Difference Vegetation Index (MAN)) to analyze the dominant factors in the spatial and temporal variations of mean annual β. The findings indicated that between 2000 and 2018, the mean β value for the Qinghai-Tibetan plateau was 1.25±0.60, ranging from 0.32 to 4.83, with spatial distribution progressively increasing from the southeast to the northwest. The desert class exhibited the highest average β value (1.84±0.44), whereas the Tropical tussock displayed the lowest average β value (0.49±0.09). The mean annual β showed a weak decreasing trend that was not significant. Based on all three methods, it was shown that precipitation dominated the spatial and temporal variations of annual mean β across the region. Rising temperatures and increased humidity in the Qinghai-Tibetan plateau, along with vegetation shifts, exert a negative influence on the mean annual β. Significant warming and increased precipitation provide favourable conditions for evapotranspiration, and better vegetation increases evapotranspiration and allocates more energy in the form of latent heat, leading to a decreasing trend in mean annual β. This study reveals the biogeophysical mechanism of vegetation restoration under climate change and demonstrates that β can be used as an indicator of climate regulation function in ecosystem evaluation.