The through tied arch bridge is an arch-girder composite system with good robustness, however, there were still bridge collapse accidents caused by systematic failure of suspenders. Taking the Nanfang’ao Bridge as an example, the causes of the collapse of the bridge are preliminarily analyzed according to the film data retained on- site. The Simple-Jonhson-Cook material failure model in LS-DYNA is used to reverse the accident process. The analysis results show that the Nanfang’ao Bridge was located in a humid environment, which makes it easy for corrosion damage to occur to bridge components. At the same time, the lack of detailed management and maintenance was the structural external cause of the bridge’s collapse. The serious damage to the suspenders themselves and the anchoring system was the structural internal cause of the systematic failure of the suspenders and the collapse of the bridge.