Objective:　To　explore　the　biomechanical　mechanism　of　aortic　insufficiency　(AI)　after　single　aortic　valve　replacement　(SAVR)　in　children　and　propose　the　corresponding　countermeasures.　Methods:　The　idealized　aortic　valve　model　and　postoperative　growth　model　were　constructed.　By　changing　the　length　of　leaflet　free　edge,　leaflet　height　as　well　as　improving　the　design　with　a　concave　structure,　the　effects　of　different　structure　dimensions　on　movement　synchronization　and　closing　performance　of　the　aortic　valve　after　surgery　were　compared.　Results:　The　closure　of　the　replacement　leaflet　lagged　behind　the　autologous　leaflet,　which　fitted　2　mm　below　free　edge　of　the　replacement　leaflet.　AI　occurred　6　years　after　operation.　Increasing　leaflet　height　could　not　improve　the　postoperative　effect　and　would　increase　the　maximum　stress　of　the　leaflet.　Increasing　free　edge　length　by　10%　could　improve　the　postoperative　outcomes,　while　increasing　free　edge　length　by　15%　would　cause　the　leaflet　to　be　too　long,　hence　resulting　in　a　poor　fit　of　the　aortic　valve.　Compared　with　the　traditional　structure,　the　concave　structure　was　more　beneficial　for　closing　performance　of　the　aortic　valve,　and　it　could　effectively　reduce　the　maximum　stress　by　20%　with　the　best　effect.　Conclusions:　The　leaflet　movement　will　be　out　of　synchronization　after　SAVR,　the　point　of　convergence　will　be　shifted,　and　AI　will　appear　6　years　after　surgery.　It　is　recommended　to　use　a　concave　structure　with　free　edge　length　increased　by　10%,　while　increasing　leaflet　height　is　not　recommended.　Copyright　©　2021　by　the　Editorial　Board　of　Journal　of　Medical　Biomechanics.