[Objective] The regulatory effectiveness of S-shaped vegetation dams with varying flow path width ratios on debris flows were analyzed to explore the role of bioengineering measures in energy dissipation and disaster mitigation, in order to provide a theoretical foundation for constructing an eco-geotechnical synergistic disaster mitigation model. [Methods] Flume experiments were conducted on vegetation dams with S-shaped flow paths and width ratios of 0% (S₀), 30% (S₃₀), 45% (S₄₅), 60% (S₆₀), and 75% (S₇₅). These tests focused on the flow velocity regulation, flow volume regulation, sediment control, and energy dissipation. [Results] ① The vegetation dam with a 0% flow path width ratio (S₀) exhibited impressive debris flow interception capabilities, reducing 31.03%—44.19% of the flow velocity, 45.88%—56.02% of the flow volume, 34.37%—52.72% of energy dissipation levels, meanwhile, it also achieved an increase in sediment interception rate of 3.31%—75.69%. ② The vegetation dam with a 75% flow path width ratio (S₇₅) showed strong sediment discharge capabilities, reducing 7.69%—29.03% of flow velocity, and 2.94%—35.54% of flow volume, and 11.56%—34.09% of energy dissipation levels, meanwhile, it also achieved and increase in sediment interception rafe of 4.13%—45.69%. ③ The vegetation dam with a 45% flow path width ratio (S₄₅) demonstrated a balanced performance in interception and discharge compared to S₃₀ and S₆₀. It reduced 11.11%—40.00%, 16.47%—51.20%, 1.63%—54.75% of flow velocity, flow volume, and energy dissipation, respectively. The interception rate of the plant dam reached 18.04%—45.16%. [Conclusion] An S-shaped vegetation dam with a 0% flow path width ratio (S₀) is ideal for debris-flow channels focused on interception. In contrast, a width ratio of 75%(S₇₅) was better suited for channels that prioritize sediment discharge. The 45% width ratio (S₄₅) effectively balances the interception and discharge.