This　study　was　designed　to　investigate　the　effect　of　sinotubular　junction　and　sinus　diameters　on　aortic　valve　closure　to　prevent　the　regurgitation　of　blood　from　the　aorta　into　the　left　ventricle　during　ventricular　diastole.　The　2-dimensional　geometry　of　a　base　aortic　valve　was　reconstructed　using　the　geometric　constraints　and　modeling　dimensions　suggested　by　literature　as　the　reference　model　A　(aortic　annulus　diameter　(DAA)　=　26,　diameters　of　sinotubular　junction　(DSTJ)　=　26,　sinus　diameter　(DS)　=　40),　and　then　the　DSTJ　and　DS　were　modified　to　create　five　geometric　models　named　as　B　(DSTJ　=　31.2,　DS　=　40),　C　(DSTJ　=　20.8,　DS　=　40),　D　(DSTJ　=　26,　DS　=　48),　E　(DSTJ　=　26,　DS　=　32)　and　F　(DSTJ　=　31.2,　DS　=　48)　with　different　dimensions.　Fluid　structure　interaction　method　was　employed　to　simulate　the　movement　and　mechanics　of　aortic　root.　The　performance　of　the　aortic　root　was　quantified　in　terms　of　blood　flow　velocity　through　aortic　valve,　annulus　diameter　as　well　as　leaflet　contact　pressure.　For　comparison　among　A,　B　and　C,　the　differences　of　annulus　diameter　and　leaflet　contact　pressure　do　not　exceed　5%　with　DSTJ　increased　by　1.2　times　and　decreased　by　0.8　times.　For　comparison　among　A,　D　and　E,　annulus　diameter　was　increased　by　6.92%　and　decreased　by　7.87%,　and　leaflet　contact　pressure　was　increased　by　8.99%　and　decreased　by　12.14%　with　DS　increased　by　1.2　times　and　decreased　by　0.8　times.　For　comparison　between　A　and　F,　annulus　diameter　was　increased　by　5.10%,　and　leaflet　contact　pressure　was　increased　by　13.54%　both　with　DSTJ　and　DS　increased　by　1.1　times.　The　results　of　leaflet　contact　pressure　presented　for　all　models　were　consistent　with　those　of　aortic　annulus　diameters.　For　the　Ross　operation　involves　replacing　the　diseased　aortic　valve,　aortic　valve　closure　function　can　be　affected　by　various　sinotubular　junction　and　sinus　diameter.　Compared　with　the　sinus　diameters,　sinotubular　junction　diameters　have　less　effect　on　the　performance　of　aortic　valve　closure,　when　the　diameter　difference　is　within　a　range　of　20%.　So　surgical　planning　might　give　sinus　diameter　more　consideration.