Abstract: Bank collapse is a common natural phenomenon in the process of river channel evolution in the middle reaches of the Yangtze River, posing certain threats to flood control safety, navigation operations, riverside infrastructure, and the utilization of water and sediment resources. In recent years, due to adjustments in local river morphology and the prolonged service life of some revetment works, the frequency of bank collapse along the protected slopes in the main stream of the middle and lower reaches of the Yangtze River has shown an increasing trend. Further clarifying the influencing factors and mechanisms of bank collapse in these protected slopes is of great significance for river management in the region. This paper selects the bank collapse incident that occurred in the Tuanjie Sluice river section in March 2025 as a typical case study, analyzing the causes from perspectives such as geological conditions, hydrological conditions, riverbed deformation, and human activities. The study concludes that the primary causes of the bank collapse at the protected slope of Tuanjie Sluice are poor geological conditions and sustained near-bank water flow erosion. Additionally, sudden water level drops and ship-induced waves from vessel navigation also contributed to the collapse of the protected slope. Based on this, emergency protection suggestions for the Tuanjie Sluice bank section and medium-to-long-term management strategies were further proposed.