To investigate the synergistic impacts of climate change and human activities on terrestrial water storage(TWS) in Henan Province, this study integrated GRACE/GRACEFO gravity satellite data and meteorological observations from 2003 to 2022. A multi dimensional analytical framework was established by combining Theil Sen Median trend analysis, Mann Kendall significance test, and the optimal parameters based geographical detector model, to reveal the spatiotemporal evolution and driving mechanisms of TWS in Henan Province. The results show that the interannual variation of TWS exhibited a trend of decreasing first and then increasing, with a declining rate of -1.279 mm/a and significant seasonal fluctuations. Precipitation recharge in the wet year of 2004 pushed TWS to its peak (25.25 mm), while the extreme drought event in 2019 reduced TWS to a historical low value (-27.42 mm). Spatially, TWS presented a pattern of high values in the southwest and low values in the northeast. The Yellow River Basin and Hai River Basin became regions with significant TWS depletion due to drought and groundwater overexploitation, whereas the Huai River Basin effectively mitigated the TWS decline through inter basin water transfer and ecological restoration. Precipitation was the dominant factor controlling TWS variation, but the contribution rates of temperature and elevation have increased significantly since 2015, reflecting the combined effects of climate warming and human activities. The interaction of multiple factors showed nonlinear enhancement, and the explanatory power of combinations such as precipitation elevation and temperature potential evapotranspiration far exceeded that of single factors, revealing the complex mechanism by which natural and anthropogenic factors synergistically regulate TWS.