Based　on　the　diseases　disposal　project　of　Longmen　Tunnel　in　the　Fujian　provincial　road　206,　the　seismic　reinforcement　measure　of　mountain　tunnel　cavity　was　studied　in　this　paper.　The　seismic　stability　of　the　mountain　tunnel　to　deal　with　the　cavity　behind　the　lining　was　calculated　and　analyzed　under　the　two　common　disease　reinforcement　measures,　by　using　a　3-D　finite　difference　method.　And　the　optimal　reinforcement　scheme　also　had　been　determined.　The　results　show　that　mortar　bolt　and　cover　arch　can　change　the　maximum　principal　stress　spectral　characteristics　of　surrounding　rock,　which　is　beneficial　to　the　seismic　resistance.　And　the　results　also　show　that　mortar　bolt　has　slightly　effect　on　the　bending　moment　stress　of　lining.