A new type of triangular prism artificial fish reef has been widely used in the channel regulation project in the upper reaches of the Yangtze River,playing an important role in improving water flow dynamics and creating fish habitats.This study investigates the flow field characteristics on triangular prism artificial fish reefs under different inflow velocities and deployment spacings using numerical simulation methods,and proposes the optimal arrangement of artificial fish reefs.The research results show that the maximum velocity of upwelling is proportional to the inflow velocity,while the upwelling volume,the maximum height-to-reef height ratio of upwelling,the volume and length of back-eddy flows are not significantly affected by the inflow velocity.Under the same flow velocity,both the volume of upwelling and back-eddy flows are inversely proportional to the lateral spacing of artificial fish reef deployment,and they initially increase and then decrease with the longitudinal spacing.The optimal deployment configuration for artificial fish reefs occurs when the lateral and longitudinal spacings are 0.5 times and 4 times the reef length,respectively.Compared with different inflow velocities,the characteristics parameters of upwelling and back-eddy flow regions are more significantly influenced by the deployment spacing of artificial fish reefs.The research conclusions can provide theoretical basis for the construction of ecological artificial fish reefs in the upper reaches of the Yangtze River.