In　order　to　convert　STL　model　of　arteries　with　open　border　into　a　closed　model,　topology　reconstruction,　boundary　identification　and　triangulation　of　arteries　were　investigated　in　this　paper.　First　topology　structure　of　STL　file　was　reconstructed　using　half　edge　data　structure.　On　this　condition,　every　border　segments　of　STL　model　can　be　identified　by　a　process　of　edge　searching.　Then　constrained　Delaunay　triangulation　with　Steiner　point　insertion　was　used　to　triangulate　the　border　regions　of　STL　model.　Base　on　this　method　automatic　software　was　developed　to　solve　this　problem.　The　results　show　that　this　method　and　corresponding　software　can　convert　STL　model　of　arteries　with　open　regions　into　closed　model.　It　provides　necessary　foundation　to　further　finite　element　volume　mesh　generation　and　hemodynamic　numerical　simulation.