To determine the rationality and basic design parameters of the simulated natural fishway layout at Longxikou Navigation-power Junction in Minjiang River,we carry out fish resource investigation and swimming ability tests for the project river.The relationship between the size of the fishway chamber and the flow velocity inside the chamber is verified by three-dimensional numerical simulation calculations,and the hydraulic parameters such as the flow pattern and control section velocity in the fishway are studied by physical model tests.We propose the design scheme of a simulated natural fishway:1)The fishway inlet is arranged at the tailrace channel end of the power plant to lure fish by tailwater from power generation and water replenishment facilities are installed at the inlet.2)The fishway adopts a lotus root type + trapezoidal cross-section structure with transverse diaphragms inside and both the fishway and diaphragms are stacked with natural pebbles.3)A slow flow platform is set up on the left bank of the downstream river to eliminate the upstream flow velocity barrier of fish.The test results show that the diversity of flow patterns and the flow velocity inside the simulated natural fishway pool at Longxikou meets the fish passage requirements.