Abstract: The study aimed to explore the effectiveness of coconut fiber mesh in reducing runoff and sediment yield on engineering accumulation slope surfaces under the condition of hydraulic erosion and runoff scouring. The study utilized simulated runoff scour experiments to investigate the runoff and sediment yield patterns, hydrodynamic characteristics, and surface runoff scour rill erosion morphology of engineering accumulation under different inflow rates (1.4, 2, 2.6, and 3.2 L/min) and coconut fiber mesh covers with two different mesh sizes (5 cm and 10 cm). The results indicated the following: 1) A mesh with a 10 cm aperture size extended the initial runoff time on the engineering accumulation slope by 11 to 27 seconds, while the 5 cm mesh size increased the time by 35 to 41 seconds. The 10 cm mesh significantly reduced surface runoff on the engineering accumulation slope by 10.21% to 15.65%, while the 5 cm mesh reduced runoff by 12.12% to 20.73%. Similarly, the 10 cm mesh reduced sediment yield on the engineering accumulation slope by 25.20% to 33.64%, and the 5 cm mesh resulted in a more substantial reduction of 42.58% to 73.06%. 2) The application of the mesh on the engineering accumulation slope significantly increased the resistance coefficient, reducing water flow velocity, shear stress, and runoff power. It also decreased the size and connectivity of erosion rills and drop structures on the engineering accumulation slope, enhancing the runoff and sediment reduction benefits. The 5 cm mesh, with its denser grid, exhibited a stronger ability to intercept water and sediment compared to the 10 cm mesh. 3) Under the condition of coconut fiber mesh coverage on the engineering accumulation slope surface, there was a significant linear relationship between the average rill width and both surface runoff and sediment yield (p<0.05). In terms of runoff, the fitting slope for the 5 cm mesh (24.25) was greater than that of the 10 cm mesh (19.15) and the bare slope (14.43), indicating that the 5 cm mesh provided better runoff reduction benefits. Regarding sediment yield, although the fitting slope for the 5 cm mesh (0.70) was between the values for the 10 cm mesh (0.66) and the bare slope (0.74), the intersection of the fitting lines for the 5 cm and 10 cm meshes occurred at x=33.75. This suggests that, during the ephemeral rill erosion stage, the 5 cm mesh had superior sediment reduction performance compared to the 10 cm mesh. Coconut fiber mesh, with its porous structure and grid layout, played an effective role in reducing runoff and sediment yield on the engineering accumulation slope. The internal voids of the coconut rope retained sediment in the runoff, reducing runoff shear force and power, stabilizing the slope, and inhibiting the expansion of erosion rills. The grid layout evenly distributed sediment deposition, forming low soil banks, slowing down the flow velocity, and promoting water infiltration, and effectively reduced soil erosion on the engineering accumulation slope. The study results provide scientific data to support the design of comprehensive soil and water conservation measures for the slopes of engineering accumulation in construction projects. Additionally, the study offers new insights into the selection of temporary protective measures for engineering accumulations.