South-to-north water transfer project is a large project aimed at alleviating the serious water resource shortage in northern China. The eco-environment quality of the water source area is directly related to water quality, safety, and long-term operation of the water transfer project. Further, it has important effects on regional, social, and economic development. In the present study, the eco-environmental vulnerability of Hanzhong City, which is located midway along the route of the south-to-north water transfer project, was quantitatively evaluated by using "pressure-state-response" model and spatial principal component analysis based on remote sensing and GIS technology. The results showed that:1) the eco-environmental vulnerability of Hanzhong City was at a medium level and was determined by the interaction of human activities and natural environment. The elevation, annual average precipitation, annual average temperate, per capita gross domestic product (GDP), and soil erosion intensity were the main driving factors. 2) In addition, the eco-environment vulnerability varied with altitudinal gradient. Vulnerability of the medium and high-medium mountain areas was higher than that of the high mountain area, and it was low in the low mountain and hill-gully areas. 3) Among the administrative divisions, the areas with high eco-environment vulnerability were mainly distributed in the Zhenba, Xixiang, Foping, Lueyang, and Ningqiang counties; the areas with low vulnerability were located in the Hantai district. 4) The regional eco-environmental vulnerability of Hanzhong City had strong spatial autocorrelation. The spatial variation was larger in the direction of 45° and 135°. It could provide theoretical and scientific basis for ecological restoration and planning of regional sustainable development of the water source midway along the route of the south-to-north water transfer project.