Affected by climate change and human activities, the surface environment and water-carbon fluxes on the Loess Plateau have significantly changed in recent decades, profoundly impacting regional water resources and ecosystems. Understanding the spatio-temporal variations of water-carbon fluxes in relation to climate change and human activities is crucial for the sustainability of water resources and ecosystems, especially in such a region strongly influenced by human activities. In this study, the remote sensing-based Vegetation Interface Processes (VIP) model was employed to reproduce spatio-temporal patterns of evapotranspiration (ET) over the Loess Plateau since the implementation of the Grain for Green Project. Validated with eddy covariance fluxes, GRACE Terrestrial Water Storage Anomaly (TWSA) and stream discharge, the model predictions were proved to be reliable. Results showed that the ET increased significantly (P < 0.05) in most parts of the Loess Plateau with a rate of 3.77 mm/a. The spatial pattern of ET trend was basically consistent with that of the Normalized Difference Vegetation Index (NDVI) trend. The most prominent increase of ET was observed in the hilly-gully areas along the middle reaches of the Yellow River, while a pronounced downward tendency was detected in agricultural areas such as the southern Yinchuan Plain of Ningxia Autonomous Region and the eastern Guanzhong Plain of Shaanxi Province, with a rate of -5.68 mm/a. The attribution analysis based on partial least squares regression (PLSR) approach showed that there were significant differences in the contributions of each driving factor to ET changes in different areas. The regional average relative contributions (RC) of climate drivers and NDVI in areas where ET significantly increase were 14.7% and 78.6% (RC of human activities was 70.5%), while those in areas where ET significantly decline were -58.4% and -31.5% (RC of human activities was -31.6%), respectively. It indicated that human activities and climate change dominated ET changes in ET significantly increase and ETsignificantly decrease areas, respectively. In climate-dominated areas, air temperature and precipitation were the dominant meteorological factors for the increase of the ET in energy-limited regions (mainly in middle to high mountain areas) and water-limited regions (mainly in desert grassland areas), respectively. The decline in sunshine duration and wind speed owing to the increase of aerosol concentration notably inhibited crop carbon assimilation and transpiration, accounting for the decrease of ET in agricultural areas. This study highlights the divergent responses of ET and the varying drivers in different regions of the Loess Plateau.