Abstract: Nest-shaped (or arch) bank collapsing in the Lower Yangtze River is the instability and failure phenomenon of bank slope under the interaction of water and soil. It has the characteristics of strong randomness, short formation time and large amount of soil collapse. After the occurrence, a "Ω" shaped or semi- circular collapsing appears. The mechanism of collapsing in is complex and the law is difficult to find out. There are two types:① the continuous collapse of large soil mass accompanied by water scouring; ② Lateral sliding of large soil mass due to liquefaction layer in soil mass. Most of the cave collapses occur in the flood season and the flood retreat period, and the relationship with the coming water and sediment conditions is not obvious. On the whole, it shows the distribution characteristics of more in the south bank and less in the north bank, and it is more likely to occur in the curved concave bank, the head and tail of the continent and the boundary mutation section of main channel of Yangtze River. At present, the simulation technology and early warning technology of arch collapse are not mature. The treatment technology is the combination of cave pond rescue and subsequent reconstruction. The temporary flood retaining embankment is set to prevent the river water from flowing back and ensure the flood control safety; The emergency rescue of the pit pond was implemented through en-gineering measures such as "guarding two shoulders, consolidating the periphery, promoting siltation first and sealing later". In view of the phenomenon of arch collapse in the lower reaches of the Yangtze River, this paper discusses its formation mechanism and distribution law, and comments on the cor-responding control technologies.