The　dynamic　characteristics　of　a　site　play　a　crucial　role　in　the　seismic　response　of　underground　structures.　However,　existing　seismic　vulnerability　models　often　inadequately　account　for　variability　in　soil　parameters.　This　paper　examines　a　frame　subway　station　underground　structure,　performing　both　a　traditional　seismic　vulnerability　analysis　considering　only　seismic　motion　record　uncertainty,　and　a　comprehensive　analysis　incorporating　uncertainties　in　soil　dynamic　parameters.　These　parameters　include　soil　shear　wave　velocity　and　three　additional　parameters　reflecting　the　soil＇s　nonlinear　dynamic　behavior.　The　Incremental　Dynamic　Analysis　(IDA)　method　was　used　to　develop　both　the　traditional　seismic　fragility　curves　and　the　curves　incorporating　these　additional　uncertainties.　Differences　between　these　two　curves　were　quantified　and　compared　using　the　Wasserstein　distance.　The　results　indicate　that　ignoring　soil　dynamic　parameter　uncertainty　significantly　impacts　the　assessment　of　post-earthquake　failure　probability　for　underground　structures.　This　impact　varies　with　seismic　motion　intensity,　and　the　discrepancy　between　the　two　seismic　fragility　curves　increases　as　the　performance　level　of　the　assessed　structure　rises.