Abstract: To enhance the energy dissipation efficiency of stepped spillways and reduce negative pressure zones, this study proposes installing trapezoidal energy-dissipating blocks with varying inclination angles at step edges, forming a novel trapezoidal block-stepped combined energy dissipator. Through hydraulic model experiments and numerical simulations, the hydraulic characteristics of blocks with inclination angles of 45°,50°, 56°,63°and 72°were investigated under varying discharges (Q) and compared with traditional stepped dissipators. Key findings indicate:①With increasing discharge, the flow regime progressively transitions from transitional flow to fully developed skimming flow.②Longitudinal velocity profiles exhibit higher upper-layer velocities and lower bottom-layer velocities. High-velocity zones progressively coalesce into linear trajectories extending downstream, demonstrating increasingly distinct segregation from low-velocity regions, enhanced flow concentration, and improved stability.③Pressure at step recesses initially decreases then increases, with recess pressures in block-equipped sections exceeding those in non-block sections; negative pressures occur at block crowns and leeward surfaces in block-equipped sections versus at step noses in non-block sections, while negative pressure zones are significantly smaller than in conventional stepped dissipators.④Under increasing discharge, the composite dissipator consistently achieves superior energy dissipation efficiency compared to conventional designs, with the influence of block inclination angle progressively diminishing and peak efficiency attained at θ=50°.