Abstract: Simplified arched roadway in layered rock to cantilever rock beam model, by stress state analysis of any three stratums, we considered the friction effect between stratum and stratum caused by stratum flexural deflection, and iterated size and transmission relationship of compressive stress of any stratum beard from strata that above it. We calculated the horizontal stress in layered rock mass, determined each strata and the location of damage, and considered arched roadway in layered rock was easily failure at spandrel. The failure mechanism is validated by Hecaogou Coal Mine's 5^# return air roadway.