Coordinating the relationship between engineering construction and the ecological environment is an important part of green sustainable development. The discharge of groundwater during the operation of mountain tunnels will alter the local hydrogeological environment of the tunnel site to some extent, which may bring about local plant ecological problems. However, the ecological degradation of terrestrial vegetation is not only affected by groundwater, but also closely related to the climate environment and plant species. The integrated model of rainfall recharge, atmosphere transpiration, plant water intake, soil water transport and groundwater seepage is established, and an ecological analysis method evaluating the influences of tunnel drainage on terrestrial vegetation is proposed to comparative study the quantitative effects and characteristic differences under different hydrogeology and climate, rainfall and sunshine conditions in different geographical regions of southeast, southwest and northwest in China. The controlling drainage is proposed for preventing the ecological degradation of terrestrial vegetation. This study will provide important support for theoretical methods and data analysis for ecologically controlling the drainage in mountain tunnels in China.