Paralleled　high-voltage　SF6　circuit　breakers　with　a　highly　coupled　split　reactor　(HCSR)　have　an　excellent　interruption　performance,　because　it　is　expected　that　this　structure　could　realize　the　function　of　automatic　current-sharing　when　the　current　flow　through　both　branches　and　automatic　current-limiting　when　the　current　flow　through　only　one　branch.　In　this　paper,　a　mathematical　model　had　been　built　for　this　interrupting　device　by　coupling　the　equivalent　circuit　equations　into　the　magneto-hydro-dynamics　(MHD)　arc　model.　The　influence　of　different　factors　including　different　operation　moments,　different　filling　pressures　and　different　inductances　are　investigated.　The　dielectric　recovery　strength　after　the　interruption　processes　is　also　investigated.　The　simulation　results　show　that　the　paralleled　high-voltage　SF6　circuit　breakers　with　a　highly　coupled　split　reactor　have　excellent　interruption　performance.　The　automatic　current-sharing　and　current-limiting　functions　of　the　HCSR　under　different　interruption　conditions　all　show　excellent　performance,　and　the　252 kV　paralleled　SF6　circuit　breakers　with　HCSR　has　successfully　interrupted　252 kV/101 kA　short　circuit　current　in　state　laboratory　of　China　recently.　©　2020,　Springer　Nature　Switzerland　AG.