Strength　reduction　method　and　ADINA　software　are　adopted　to　study　the　stability　of　submarine　tunnel　structures　subjected　to　seepage　and　earthquake　under　different　seawater　depths　and　overlying　rock　strata　thicknesses.　First,　the　excess　pore　water　pressure　in　the　rock　mass　is　eliminated　through　consolidation　calculation.　Second,　dynamic　time-history　analysis　is　performed　by　inputting　the　seismic　wave　to　obtain　the　maximum　horizontal　displacement　at　the　model　top.　Finally,　static　analysis　is　conducted　by　inputting　the　gravity　and　the　lateral　border　node　horizontal　displacement　when　the　horizontal　displacement　is　the　largest　on　the　top　border.　The　safety　factor　of　a　subsea　tunnel　structure　subjected　to　seepage　and　earthquake　is　obtained　by　continuously　reducing　the　shear　strength　parameters　until　the　calculation　is　not　convergent.　The　results　show　that　the　plastic　zone　initially　appears　at　a　small　scope　on　the　arch　feet　close　to　the　lining　structure　and　at　both　sides　of　the　vault.　Moreover,　the　safety　factor　decreases　with　increasing　seawater　depth　and　overlying　rock　strata　thickness.　With　increasing　seawater　depth　and　overlying　rock　strata　thickness,　maximum　main　stress,　effective　stress,　and　maximum　displacement　increase,　whereas　displacement　amplitude　slightly　decreases.