Abstract: The weir-flume combination facility is advantageous for flow monitoring in mountainous areas.The sediment distribution behind the weir and the downstream erosion can be affected by arm slope owing to the changes in the hydrodynamic characteristics of the weir-flume combination facility.To further explore the influence of arm slope on the flow turbulence characteristics of the weir-flume combination facility, the bottom flow characteristics under different flow rates, bottom slope, and arm slope were analyzed based on the hydraulic performance test.The distribution law of velocity, turbulence kinetic energy, and bed surface shear stress were obtained, and the mechanism of flow energy dissipation and erosion was revealed during the operation.The research results show that the arm slope affects the lateral flow distribution.The increase in arm slope causes the water flow to be concentrated in the middle, and the flow behind the weirs on both sides is strengthened, which increases the risk of retrogressive scour.Compared with the Reynolds shear stress method, the modified turbulent kinetic energy method is more suitable for calculating the bed surface shear stress behind the facility.The larger values of the bed surface shear stress are mainly concentrated in the area behind the weir on both sides.Large-scale vortex structures are mainly focused on both sides of the flume outlet, while other vortex areas are distributed in the area behind the weir on both sides.The increase in the arm slope and bottom slope leads to an increase in turbulent intensity and turbulent energy on both sides behind the weir, which intensifies the energy dissipation of the water flow under the weir and effectively improves the energy dissipation rate of the facility.