Abstract: Changes in water flow conditions and riverbed deformation can affect the suitability of fish habitat. To quantitatively evaluate and predict the impact of different bifurcation river sections in the middle and lower reaches of the Yangtze River on fish habitat, we selected Chinese carp as the target fish species and constructed a corresponding ecological hydraulic model by using model simulation. Habitat indicators for the fish under different flow conditions for adults and juveniles was obtained. The results showed that the suitability of adult fish habitat in the two river sections increased with increasing flow, while the suitability of juvenile fish habitat increased first and then decreased with increasing flow. In addition, in the long term, the suitability of fish habitat will decrease over time. After 20 years, due to changes in water dynamics caused by riverbed deformation, the two river sections may no longer be suitable for the survival of Chinese carp.