The deep-buried long tunnel group at Jinping Ⅱ Hydropower Station has an average buried depth of 1500～2000m with high stress and complex engineering geological conditions which lead to difficult groundwater treatment. Groundwater treatment for this project was done in stages. First, survey was performed for the outlet tunnel section; then, the outlet points and sections with small flow and sub-large flow were blocked on the surface, and the deep surrounding rock was reinforced to form a uniform anti-seepage consolidated ring of some thickness; finally, the concentrated water gushing point was sealed off. After treatment, the inspection results all met the standard and achieved the expected treatment effect.