Different　surgical　procedures　in　coronary　artery　bypass　grafting　(CABG)　will　cause　different　hemodynamic　environments,　which　will　affect　the　surgical　result　and　long-term　patency.　In　this　study,　the　hemodynamic　effect　of　the　Y-type　graft　was　discussed　by　comparing　it　with　normal　graft.　A　patient-specific　3-dimensional　(3D)　model　of　coronary　artery　with　serious　stenosis　was　reconstructed.　Two　different　surgical　procedures　were　applied　on　the　3D　model　through　the　virtual　surgery,　the　normal　graft　and　the　Y-type　graft.　Thus,　two　3D　models　with　different　grafts　were　built.　The　zero-dimensional　(0D)/3D　coupling　method　was　used　to　perform　the　numerical　simulation　by　coupling　the　3D　artery　model　with　a　0D　lumped　parameter　model　of　the　cardiovascular　system.　The　coronary　flow　rate　and　the　graft　flow　were　calculated　and　illustrated　in　this　paper.　The　wall　shear　stress　(WSS)　and　oscillatory　shear　index　(OSI)　were　also　calculated　and　depicted.　The　short-term　outcomes　of　the　normal　graft　and　Y-type　graft　are　almost　the　same.　But　the　long-term　patency　of　the　Y-type　graft　is　worse.　Moreover,　decreasing　the　diameter　of　the　graft　to　LCX　may　get　higher　WSS　and　provide　enough　flow　at　the　same　time.