Based　on　the　non-linear　soil-structure　interaction　model　for　a　two-storey　and　three-span　metro　station　in　a　typical　underground　engineering　site,　an　IDA　(incremental　dynamic　analysis)-based　structural　seismic　fragility　analysis　method　is　introduced　for　underground　metro　station　structures.　The　earthquake　intensity　measure　IM　suitable　for　the　underground　structures　is　proposed,　and　the　change　of　their　seismic　response　with　the　increase　of　earthquake　amplitude　is　preliminarily　discussed.　The　seismic　fragility　curves　of　shallow-buried　metro　station　structures　are　established,　and　the　failure　probability　of　structures　under　different　seismic　intensity　levels　is　obtained.　The　results　show　that　PGA　is　an　appropriate　IM　under　non-free　field,　and　comparison　of　the　numerical　results　with　the　fragility　curve　of　other　scholars　shows　that　the　proposed　fragility　analysis　method　is　feasible,　and　can　quantitatively　give　the　failure　probability　of　structures　at　different　performance　levels,　and　provide　reference　for　seismic　design　of　underground　structures.　©　2020,　Editorial　Office　of　Chinese　Journal　of　Geotechnical　Engineering.　All　right　reserved.