Significant climate change and vegetation greening have been detected over the past decades in China. Acting as a key variable in climate system and soil-plant-atmosphere continuum, root zone soil moisture (RZSM) is fundamental to understanding land-atmosphere interactions under a changing environment. Based on two stateof-the-art RZSM datasets and geographical detector model, this study quantified the contributions of diverse drivers to RZSM variations at both national and climatic zone scales in China during 1982-2022. The spatiotemporal variability of climate was identified as the key driver that has shaped spatial pattern and dominated temporal evolution of RZSM at both scales in China. Climate, vegetation, soil properties, topography, and agricultural management contributed 33.73%, 23.51 %, 19.93 %, 18.16 %, and 4.68 % to the spatial stratified heterogeneity of RZSM in China, respectively. Furthermore, the relative contribution of climate has increased significantly in China, humid, and semi-humid regions, while decreased significantly in arid and semi-arid regions over the past four decades, indicating the strengthening dominance of climate in shaping the spatial pattern of RZSM in China, particularly in regions with relatively humid climate conditions. With regard to temporal evolution, climate change and vegetation change contributed 93.96 % and 6.04 % to RZSM variations in China, respectively. The contribution of climate change was relatively higher in drier regions (arid and semi-arid regions) and wetter seasons (summer and autumn), while lower in wetter regions (humid and semi-humid regions) and drier season (winter). This study implied that RZSM variability would become more complicated in response to climate change, which can subsequently alter the related processes of water balance and energy budget through RZSM-climate feedbacks and should be taken seriously in future studies.