A　novel　1200　V　4H-SiC　junction　barrier　Schottky　diode　(JBS)　with　built-in　MOSFET(MJBS)　structure　is　proposed　and　simulated　with　Sentaurus　TCAD.　The　characteristics　of　forward　conduction　and　reverse　blocking　of　conventional　JBS　and　proposed　MJBS　with　different　channel　widths　are　investigated.　The　MJBS　exhibits　a　lower　forward　voltage　drop　and　better　reverse　breakdown　characteristics　than　that　of　the　JBS,　which　attributes　to　high-reliability　applications.　In　addition,　a　local　heavy　doping　concentration　is　adopted　in　MOSFET　channel　region,　which　can　reduce　the　on-state　resistance　of　the　gate　accumulation　layer　and　reduce　the　possibility　of　early　device　breakdown　due　to　the　increase　of　channel　doping　concentration.　©　2021　ACM.