Study region: Qinling-Daba Mountains region (QB) in central China. Study focus: Vegetation changes significantly influence the water cycle in different regions. However, the response of water yield (defined as precipitation minus evapotranspiration) to vegetation greening in QB remains unclear. In this study, we used a water vapor tracer (WVT) method embedded in a regional climate model (WRF) to quantify the response of water yield to vegetation greening during the growing season in the QB. New hydrological insights for the region: Vegetation greening could increase evapotranspiration by 5.12 mm month- 1 and precipitation by 1.20 mm month- 1, which led to the water yield decreased by 3.92 mm month- 1 (6.88 %). The enhanced evapotranspiration was mainly attributed to the increase in leaf area index and vegetation fraction, and the increased precipitation was related to the enhanced evapotranspiration and changes of precipitation efficiency. In addition, vegetation greening could alter atmospheric circulations, resulting in a significant reduction in the water vapor inflow entering QB. This study clarified how the vegetation greening in QB affected the local water yield, which could help guide the sustainable ecological restoration and management of water resources in the local and surrounding areas.