The tunnel may have to be constructed across a faulted zone as it is not always possible to avoid crossing active faults. In these situations, the tunnel must tolerate the expected fault displacements and seismic action, and allow
only minor damages for the assumed life time. The seismic behavior of the tunnel across the active fault is analyzed and a method of designing flexible lining for tunnels across active fault is put up. The effects of the method are analyzed by numerical simulation. The results show the tunnel lining with flexible joints allows the tunnel to distort into S-shape through the fault zone without rupture and thus it can provide reference to the design and construction of tunnels located in the active faulted zones.