f14, f18 fault and lamprophyre veins are developed in the top arch of tailrace surge tank in underground powerhouse of Jinping I hydropower station, the fault and the influence line was exposed after excavation with broken rock, strong weathering and instable surrounding rock. Pre-stressed anchor cable was designed to strengthen the support for cavity stability and construction safety. The papermainly introduced the construction method for anchor cable with large-angle upward hole in tailrace surge tank.