Taking　a　rigid-frame　tied　through　CFST　arch　bridge　as　a　study　object,　a　finite　element　model　was　built　with　the　software　ANSYS/LS-DYNA.　The　process　of　its　cable　loss　was　simulated　with　the　contact-impact　method.　The　variation　of　the　internal　forces　of　its　different　structure　members　before　and　after　cable　loss　was　analyzed　to　determine　the　potential　failure　mode　of　the　structure.　The　results　showed　that　cables,　CFST　arch　ribs　and　deck　slabs　all　bear　a　impact　due　to　a　cable　loss;　among　them,　the　influence　of　the　cable　loss　on　the　adjacent　cables　is　the　largest　and　the　variation　of　their　axial　forces　exceeds　three　times　of　their　initial　values;　therefore,　the　action　of　the　dynamic　force　which　is　far　greater　than　the　static　force　action　during　the　cable　loss　should　be　considered;　the　influence　of　cable　loss　on　the　main　girder　is　significantly　greater　than　that　on　the　arch　ribs;　the　local　collapse　of　the　deck　system　may　occur　due　to　the　insufficient　strength　of　the　weld　connection　between　transverse　beams　and　longitudinal　ones.