To determine the layout of the fish inlet of the imitation ecological fishway constructed on the left bank of the Longxikou Navigation-power Junction,this paper combines the operating conditions of the hub and the existing topographic conditions,and analyzes that the water flow conditions near the fishway inlet do not meet the fish upstream requirements under many operating conditions,and certain engineering optimization measures need to be taken.For the characteristics of the Longxikou hub,typical operating conditions are selected to study the water flow conditions at the fish inlet and downstream of the hub.Based on the research findings of a two-dimensional numerical simulation model,it is planned to optimize the water flow conditions at the fishway entrance through measures such as partially removing longitudinal weirs between the power station and spillway,excavating and dredging downstream of the tailwater slope of the power station,and reconstructing habitats on the left bank.The advantages and disadvantages of different fish inlet layout options are compared and analyzed,and it is recommended to optimize the inlet and downstream flow field of the fish passage at Longxikou estuary by using a combination of habitat reconstruction and dredging,both of which can meet the flow velocity requirements of the fish passage inlet at Longxikou estuary.The results can provide technical reference for numerical simulation and fishway inlet arrangement for other similar inlet flow conditions.