This　paper　calibrates　the　finite　element　model　(FEM)　of　a　tied-arch　bridge　using　an　automatic　model　updating　procedure　developed　within　two　softwares.　The　former　is　used　for　sensitivity　analysis　and　optimization　analysis　while　the　latter　is　responsible　for　structural　modeling　and　eigenvalue　analysis.　An　interface　connecting　two　softwares　is　first　developed,　as　well　as　the　procedure　to　calibrate　the　FEM.　Based　on　the　original　drawing　and　topographic　survey,　the　FEM　of　the　investigated　bridge　is　created.　To　obtain　the　experimental　modal　parameters,　eight　global　modes　of　the　studied　bridge　are　identified　by　ambient　vibration　tests　and　the　frequency　domain　decomposition　technique.　Then,　the　sensitivity　analysis　and　FEM　updating　procedure　is　conducted　and　the　optimal　structural　parameters　are　identified.　Finally,　the　updated　FEM　is　verified　by　a　series　of　static　tests.　Results　show　that　the　updated　model　could　better　represent　the　actual　bridge.　Therefore,　the　numerical　model　updated　by　the　proposed　procedure　could　be　further　used　for　damage　identification　of　the　bridge　under　service　loads.