Research conclusions：Under condition of no ground reinforcement, tunnel construction will effect the structure internal force and produce pier settlement much. After the ground is reinforced, the largest settlement and differential settlement of pier are reduced 38 percent and 44 percent resectively compared with that of no reinforcement. At the same time, the internal force of arch bridge is reduced dramatically. Compared with no reinforcement, structure internal force is decreased 25 percent to 40 percent. The spiral jet pile reinforcement method can ensure the safety of arch bridge in the course of shield tunnel construction.