The　demand　for　high-temperature-resistant　metal　rubber　seals　(MRSs)　with　a　large　ring-to-diameter　ratio　is　increasing.　In　this　work,　an　O-type　MRS　with　a　large　ring-to-diameter　ratio　was　developed　by　embedding　a　spiral　network　metal　rubber　into　a　stainless-steel　ring　with　a　special　preparation　process.　The　effects　of　the　frequency,　porosity,　and　amplitude　on　the　dynamic　performance　of　this　O-type　MRS　were　studied　in　detail.　The　mechanical　properties　of　the　MRS　were　characterized　through　dynamic　tests,　and　the　damping　sensitivity　was　analyzed　using　orthogonal　tests.　The　results　show　that　the　MRS　has　a　better　stability　under　different　vibration　frequencies.　The　energy　consumption　and　loss　factor　of　the　sample　increase　with　increasing　porosity.　With　an　increase　in　the　loading　amplitude,　the　energy　consumption　and　loss　factor　of　the　test　samples　with　the　same　porosity　increase,　whereas　the　dynamic　average　stiffness　of　the　specimen　gradually　decreases.　Furthermore,　the　range　analysis　of　the　orthogonal　experiment　shows　that　the　factors　affecting　the　damping　performance　of　the　seal　are　in　the　following　order:　porosity　＞　amplitude　＞　frequency.　This　study　presents　the　dynamic　mechanical　properties　of　O-shaped　MRSs　with　a　large　ring-to-diameter　ratio　and　provides　a　foundation　for　their　engineering　application.