A　novel　silicon　carbide　(SiC)　U-shape　trench　MOSFET(UMOSET)　with　the　vertical　field　plate　coupled　floating　island　structure　(VFF-UMOSFET)　is　proposed.　Double　epitaxial　layer　is　adopted.　Simulations　study　is　performed　using　Sentaurus　TCAD.　The　effect　of　the　field　plate　and　floating　island　on　the　electric　field　distribution,　breakdown　voltage　and　specific　ON-resistance　(sRON,　sp)　are　studies　and　the　relationship　between　doping　concentration　and　breakdown　voltage　in　the　first　drift　zone　and　the　second　drift　zone　is　discussed　respectively.　The　simulation　results　show　that　the　VFF-UMOSFET　with　the　vertical　field　plate　coupled　floating　island　structure　exhibits　a　higher　figure　of　merit　related　to　the　breakdown　voltage　and　the　specific　on-resistance,　which　is　improved　by　37.5%　and　65%,　respectively,　with　comparison　to　the　state-of-the-art　source　trench(ST-MOSFET)　and　reduce　the　peak　of　the　electric　field　at　the　trench-gate　bottom　by　60%,　compared　with　the　standard　UMOSFET,　while　effectively　reducing　the　electric　field　at　the　field　plate　bottom.　Finally,　the　optimization　of　parameters　(field　plate　depth,　floating　island　geometry)　is　discussed.　©　2022　Association　for　Computing　Machinery.