Abstract: In this paper, the typical Ω-collapse in the lower Yangtze River is described and analysed, including its characteristics, forming process, geological conditions, bank slope variation, and flow-sediment movement patterns. On this basis, the cause of Ω-collapse is exposed and a mathematical formula for the critical condition of the Ω-collapse is obtained.Finally, some suggestions as to how to predict and protect the Ω-collapse are put forward.