35　kV　underwater　cables　are　commonly　used　for　the　transmission　of　electrical　energy　in　nearshore　offshore　wind　farms.　Investigating　the　loss　characteristics　of　these　cables　improves　in　enhancing　the　efficiency　of　energy　transmission.　This　paper　presents　the　construction　of　a　multi-physics　coupled　electromagnetic-thermal-fluid　underwater　cable　simulation　model　using　COMSOL　software.　The　model　aims　to　calculate　the　electromagnetic　losses　in　each　layer　of　the　underwater　cable　accurately.　This　study　examines　the　influences　of　various　laying　methods,　seawater　temperature,　seawater　velocity　and　burial　depth　on　loss　characteristics　of　submarine　cables.　The　simulation　results　show　that　the　electromagnetic　loss　of　the　submarine　cable　is　spirally　distributed　along　the　cable　axis.　The　total　losses　of　the　submarine　cable　increase　with　the　increase　of　seawater　temperature　and　seawater　velocity.　Furthermore,　the　losses　in　the　shielding　layer　and　armor　layer　demonstrate　a　decline　as　cable　resistance　surges　with　temperature.　　©　2024　IEEE.