The　floating　bridge　bears　the　dead　weight　and　live　load　with　buoyancy,　and　has　wide　application　prospect　in　deep-water　transportation　infrastructure.　The　structural　analysis　of　floating　bridge　is　challenging　due　to　the　complicated　fluid-solid　coupling　effects　of　wind　and　wave.　In　this　research,　a　novel　time　domain　approach　combining　dynamic　finite　element　method　and　state-space　model　(SSM)　is　established　for　the　refined　analysis　of　floating　bridges.　The　dynamic　coupled　effects　induced　by　wave　excitation　load,　radiation　load　and　buffeting　load　are　carefully　simulated.　High-precision　fitted　SSMs　for　pontoons　are　established　to　enhance　the　calculation　efficiency　of　hydrodynamic　radiation　forces　in　time　domain.　The　dispersion　relation　is　also　introduced　in　the　analysis　model　to　appropriately　consider　the　phase　differences　of　wave　loads　on　pontoons.　The　proposed　approach　is　then　employed　to　simulate　the　dynamic　responses　of　a　scaled　floating　bridge　model　which　has　been　tested　under　real　wind　and　wave　loads　in　laboratory.　The　numerical　results　are　found　to　agree　well　with　the　test　data　regarding　the　structural　responses　of　floating　bridge　under　the　considered　environmental　conditions.　The　proposed　time　domain　approach　is　considered　to　be　accurate　and　effective　in　simulating　the　structural　behaviors　of　floating　bridge　under　typical　environmental　conditions.