Objective　To　numerically　compare　the　prospective　hemodynamic　outcomes　between　a　new　window　surgery　and　a　traditional　surgery　in　the　treatment　of　supracardiac　total　anomalous　pulmonary　venous　connection　(S-TAPVC).　Methods　A　3D　geometry　model,　composed　of　pulmonary　vein　(PV)　and　left　atrium　(LA),　was　reconstructed　based　on　summarized　data　with　S-TAPVC.　Two　surgery　models　were　established　based　on　this　model.　One　is　the　traditional　surgery　model,　where　an　elliptical　anastomosis　was　created　by　incising　and　stitching　the　LA　and　the　common　vein　(CV)　along　the　axis　of　the　CV.　The　other　is　the　new　window　surgery　model,　where　the　CV　was　incised　with　an　H-shaped　orifice,　and　LA　was　incised　with　a　transposed　H-shaped　orifice,　and　then　the　orifice　edges　were　stitched　like　a　window.　Two　models　with　a　relative　cross　sectional　area　(RCSA)　of　300　mm(2)/m(2)　and　500　mm(2)/m(2)　were　established,　which　correspond　to　traditional　surgery　and　window　surgery.　Numerical　simulation　of　hemodynamics　was　carried　out.　The　velocity,　left　atrium　and　pulmonary　vein　pressure,　the　pressure　difference　of　anastomosis　and　the　energy　conversion　efficiency　were　analyzed　to　evaluate　the　prospective　hemodynamic　outcomes　of　these　two　operations.　Results　Window　surgery　presented　a　lower　blood　flow　velocity,　pressure　difference,　and　the　WSS　at　the　anastomosis,　compared　to　traditional　surgery.　In　terms　of　energy　loss,　the　power　conversion　efficiency　of　window　surgery　was　significantly　higher　than　that　of　traditional　surgery,　with　66.8%　and　53.5%,　respectively.　Conclusion　The　new　window　surgery　demonstrates　a　lower　pressure　difference　of　anastomosis　and　higher　energy　conversion　efficiency,　which　may　be　a　better　choice　compared　with　the　traditional　surgery　for　S-TAPVC　patient.