A running tunnel of Line 3 of Nanjing Metro crosses underneath a stone arch bridge, which has to be reinforced before shield tunneling. However, due to the particular ground surface conditions, the stone arch bridge cannot be reinforced from the ground surface. Therefore, inner concrete arches are installed for the stone arch bridge and the shield boring parameters are optimized. In the end, the quality of the shield bored tunnel is ensured and the shield passes the stone arch bridge successfully. 