Abstract: Many active faults, especially strike-slip faults, exist along the Sichuan-Tibet Railway, and it is easy for strike-slip fault dislocations to make a tunnel that passes through an active fault zone suffer serious structure damages. Taking a railway tunnel that passes a fault zone as the engineering background, this paper adopts the finite-difference numerical simulation to evaluate the safety of the tunnel structure by analyzing the displacement, stress and strain of the tunnel structure under different strike-slip fault dislocations. The research shows that: with strike-slip fault dislocation, the larger the dislocation is, the greater the displacement of the tunnel structure will be except longitudinal displacement, and the greatest impact the strike-slip fault dislocation will have on the tunnel structure in the fault area and the hanging wall area; after the strike-slip fault dislocation is larger than 0.6 m, the stress on the tunnel structure is less affected by the dislocation; After the strike-slip fault dislocation is greater than 0.6 m, the tunnel structure starts to be damaged, and the damage rage increases with the increase of the dislocation.