By　taking　the　structure　of　a　two-story　two-span　subway　station　as　the　research　object,　a　two-dimensional　finite　element　model　considering　soil-structure　interaction　is　established　on　the　ABAQUS/　standard　software　platform　to　study　the　seismic　vulnerability　analysis　of　underground　structures　based　on　the　cloud　and　incremental　dynamic　analysis　(IDA)　methods.　The　model　employs　the　nonlinear　time-history　dynamic　analysis　method　to　obtain　the　dynamic　response　of　the　structure　under　the　action　of　502　original　ground　motion　records　(cloud　method)　and　44　scaled　ground　motions　(IDA　method).　Interstory　drift　ratio　is　selected　as　the　damage　measure　index,　and　PGA　is　chosen　as　the　intensity　measure　index　of　ground　motion.　The　seismic　fragility　curves　of　the　underground　subway　station　structure　are　established　on　the　basis　of　the　calculation　results　of　the　cloud　and　IDA　methods.　The　postearthquake　functional　failure　probability　of　the　underground　structure　evaluated　by　the　cloud　method　is　equal　to　that　calculated　by　the　IDA　method,　and　the　maximum　difference　between　both　values　is　only　7.　5%.　In　contrast　to　the　cloud　method,　the　seismic　vulnerability　analysis　based　on　the　IDA　method　can　assess　the　failure　probability　of　the　underground　structure　at　any　ground　motion　intensity　level　because　the　amplitude　can　be　scaled.　The　finding　mentioned　above　could　provide　a　scientific　reference　for　a　performance-based　method　for　the　analysis　of　the　seismic　design　of　underground　structures.　©　2023　Editorial　Board　of　Journal　of　Harbin　Engineering.　All　rights　reserved.