[Objective] Continuous sharp bends in river channels are prone to significant river regime adjustments and abrupt changes under the impact of unsaturated sediment-laden flow, which have far-reaching implications for flood control, navigation, and water resource utilization. This study investigates the hydraulic characteristics of the river section with sharp bends in the lower Jingjiang River and the scour and siltation characteristics of the upstream and downstream bends after the natural cutoff through large-scale physical model experiments, aiming to deepen the understanding of the natural cutoff development process and provide references for the long-term regulation and planning of the river-lake confluence section in the middle reaches of the Yangtze River. [Methods] Taking the reach from Xiongjiazhou to Chenglingji in the middle reaches of the Yangtze River as the research object, a physical model was established with a horizontal scale of 1∶400 and a vertical scale of 1∶100. The model had a total straight-line length of about 70 m, a maximum width of about 40 m, and included two continuous sharp bends and upstream and downstream transition sections. Based on the hydrological data measured at Luoshan Station from 2003 to 2020, the model test water and sediment conditions were set up with different flow conditions of flood, medium, and drought. First, the hydraulic characteristics of the bend section under different flow levels were studied through fixed-bed model tests to identify the most likely flow conditions and locations for natural cutoff. Subsequently, movable-bed scour tests were conducted, applying flow conditions favorable for cutoff to study the cutoff development process. Considering that the flow in the Jingjiang section would be in a severely undersaturated state for a long time after the Three Gorges Reservoir is impounded, the inlet water and sediment conditions in this model test were simplified to clear water. [Results] The model test results showed that after the flow overtopped the bank, the main flow belt in the upstream Qigongling bend section gradually shifted from the main channel to the convex bank side. Three velocity concentration zones were formed at the neck, middle, and leading edge of the flow, with the peak velocity decreasing stepwise from the neck to the main channel. During the natural cutoff process of the Qigongling bend, the most likely location for the breach was between 1 300 m and 1 500 m away from the rear embankment. After 3 days of scouring by the overbank flow, gullies began to form, which developed into a fully connected breach over a period of about 30 days. After cutoff, the bend apex section tends to become narrower and deeper, while the transition section tends to become wider and shallower. [Conclusion] The results provide forward-looking guidance for the governance of the middle reaches of the Yangtze River system.