In this paper, the quantitative research of accumulated gas is carried out on Luodaiguzhen Tunnel in Chengdu based on equivalent explosive energy theory; and then the fluidsolid coupling model in accordance with tunnel geometric structure is established by means of ALE technique of LSDYNA software; the tunnel lining is simulated by RHT model and key parameters are modified; the characteristics of explosive shock wave are studied and compared with calculation results of empirical analysis formula; finally, the numerical simulation results of lining damage are compared with site surveying results. The study results show that: (1) The fluidsolid coupling model can reappear the gas explosion process in tunnel. (2) Due to the tunnel lining, the explosive shock wave reflects repeatedly and irregularly, which rapidly strengthens the wave, slows down the decay and complexes the flow field; and the strongest reflection effect occurs on the corner of tunnel sidewall. (3) The lining is completely destroyed under the action of violent stamping of explosive shock wave within 5 m of explosion center and badly damaged under the action of large pressure stress and tensile stress in the scope of 5 m to 10 m of explosion center; and the damage cracks are formed under large tensile stress beyond 10 m of explosion center. The numerical simulation results of lining damage are basically consistent with the site surveying results.