Abstract: The gas explosion accident in Luodaiguzhen tunnel is the only one typical severe inner-blast case in the highway tunnels in recent years, in order to investigate the damage mechanism of tunnel lining under severe explosion effect, the equivalent and quantization of the burst source is studied, the RHT model is used to simulate the lining structure and correct some key parameters, using ALE technique in LS-DYNA to establish a fluid-structure coupled numerical model with uniform size of tunnel cross-section, the damage process of tunnel lining is obtained and its stress state is analyzed.The study show that: Within 5.1 meters of detonation the lining is developed from local destruction zone into completely destructive zone under the action of explosive shock wave dramatically stamping action; Within 5.1-10.9 meters of detonation massive damage cracks on the lining expands cut the lining structure into blocky structures form a severely damaged zone under the alternating action of tensile and compressive force; Distance from detonation beyond 10. 9 m the longitudinal and circumferential damage cracks in the lining are mainly caused by tensile stress, which is the general damage zone; The damaged part of the lining is mainly located in the arch and curved sidewalls, and the "Horn structure" in the corner of the curved side walls makes the damage particularly serious.The numerical results are basically consistent with the actual damage investigation of Luodaituzhen highway tunnel and the damage evaluation that based on SDOF approach, which indicates that the research give a reasonable method and reliable calculation parameters, and provide reference for the study of the large complex structure inner explosion or combustible gas explosion.