Study region: The Huang-Huai-Hai river basin (HHH) in China. Study focus: This investigation employs the Weather Research and Forecasting (WRF) model to quantify the hydro-climatic impacts of vegetation change. Through comparative simulations driven by 2001 and 2022 Land Use/Land Cover scenarios, this study isolates basin-scale ecohydrological responses to over two decades of vegetation restoration. New hydrological insights: Basin-wide vegetation improved substantially (LAI and FVC increased >50%). This ecological restoration significantly altered regional hydrology through distinct mechanisms: (1) In areas with pronounced greening (Loess Plateau and the mountainous regions of the Haihe river basin, M-HaiB), elevated evapotranspiration (ET, +2.69%) increased horizontal (+1.49%) and vertical (+1.35%) water vapor fluxes. (2) Approximately 55% of this ET enhancement converted to local precipitation, generating up to a 15 mm increase in the southeastern Huanghe river basin and M-HaiB. (3) Thermodynamically, vegetation change reshaped the surface energy balance by increasing latent heat flux and decreasing sensible heat flux. (4) Aerodynamically, this energy shift, combined with reduced near-surface winds and intensified vertical velocities, enhanced moisture retention and transport. Consequently, downwind regions (the northern Huanghe and the plain regions of the Haihe river basin, P-HaiB) displayed a 10 mm precipitation increase, closely associated with growing-season water vapor transport via the southeastern monsoon. These findings quantitatively elucidate basin-scale eco-hydrological-climatic coupling mechanisms.