The　engineering　characteristics　of　marine　site　are　the　important　basis　for　the　design,　construction,　operation　and　maintenance　of　major　marine　projects　and　the　research　focus　of　geotechnical　earthquake　engineering.　The　strong　ground　motion　records　of　6　seabed　stations　in　Sagami　Bay,　Japan　from　2000　to　2018　are　collected,　after　screening　and　pre-processing,　the　horizontal-to-vertical　spectral　ratio　(HVSR)　method　is　used　to　calculate　the　Fourier　amplitude　spectrum　ratio　of　each　record.　The　optimal　site　characteristics　of　Sagami　Bay　are　obtained　through　the　dynamic　clustering　learning　combined　with　the　optimal　classification.　The　results　show　that　the　dynamic　clustering　learning　method　has　strong　performance　and　robustness　for　time　series　data,　and　can　meet　the　local　and　global　resolutions.　The　site　of　Sagami　Bay　can　be　macroscopically　divided　into　submarine　canyon　area　and　basin　area.　The　dominant　period　of　the　canyon　area　is　significantly　smaller　than　that　of　the　basin　area,　and　the　high　frequency　attenuation　is　relatively　slow.　The　engineering　characteristics　of　marine　site　are　given　by　the　topographic　slope　of　the　local　site.　The　relevant　research　results　may　provide　reference　for　simulation　of　sea　ground　motion　and　construction　of　marine　projects.　©　2023　Chinese　Society　of　Civil　Engineering.　All　rights　reserved.