Abstract: Taking the sea section slurry balance TBM (tunnel boring machine) construction of Qingdao metro Line 8 as the background, the mechanical response of the shield tunnel when crossing the F4 fracture zone is simulated and calculated by using the finite difference software FLAC3D, and the stability of surrounding rock during shield tunnel construction is analyzed. According to on-site monitoring data, the reliability of the simulation is verified, and the construction parameters of the TBM in the fracture zone are discussed. Results show that when the TBM is crossing, the tunnel vertical displacement is mainly concentrating on the top and bottom of the arch, and the displacement increases significantly when TBM passes through the fracture zone; the maximum tunnel stress is mainly concentrated near the arch waist, and the tensile stress appears in the fracture zone, which is extremely unfavorable to the stability of the surrounding rock in the fracture zone. To ensure the construction quality and safety, and to prevent surrounding rock instability accidents, reinforcement measures should be taken in advance and the tunneling parameters should be controlled and adjusted at the same time.