The　seismic　resilience　of　underground　structures　is　generally　based　on　the　results　of　the　seismic　fragility　analysis　and　the　damage　of　all　the　structural　components　comprehensively.　Whereas,　the　seismic　behavior　of　underground　structures　is　greatly　influenced　by　the　vertical　ground　motions.　Therefore,　this　paper　proposed　a　new　method　to　study　the　seismic　fragility　of　underground　structures　subjected　to　both　horizontal　and　vertical　ground　motions,　and　by　considering　the　damage　weight　coefficients　of　the　structural　components　to　the　overall　structure.　Pushover/pseudo-gravity　analyses　were　conducted　to　determine　the　demand　measures　and　seismic　performance　levels　of　all　the　structural　components.　Then　the　intensity　measures　of　earthquakes　were　determined　and　the　seismic　fragility　curves　of　structural　components　were　built　by　combining　the　seismic　performance　levels　of　structural　components　and　the　3D　incremental　dynamic　analyses　on　the　underground　structures.　Meanwhile,　according　to　the　damage　probability　of　each　structural　component,　the　damage　weight　coefficients　of　components　to　the　damage　of　the　overall　structures　were　calculated.　After　that,　the　seismic　fragility　surfaces　of　the　underground　structures　were　built　and　the　seismic　fragility　of　the　structures　was　discussed.　The　method　developed　in　this　study　could　not　only　be　used　to　evaluate　the　damage　probability　of　underground　structures　caused　by　the　vertical　ground　motions,　but　also　to　evaluate　the　damage　probability　and　post　-earthquake　repairability　of　the　components.