To address the significant ecological negative impacts of traditional coastal protection engineering and the lack of a quantitative evaluation system,we build a coupled assessment framework integrating a habitat suitability index model with a three-dimensional smoothed particle hydrodynamics model.We propose a quantitative indicator called weighted usable volume to evaluate ecological benefits.Using oysters as a representative species and selecting flow velocity and water depth as key factors,we combine physical experiments and numerical simulations to compare the ecological benefit of different armor block configurations (tetrapods,regularly and randomly placed Accropodes) under regular wave action.The results show that randomly placed Accropodes provide the highest ecological benefit,with a 23.3% increase in weighted usable volume compared to tetrapods,while regularly placed Accropodes achieve a 7.9% improvement.The results of the study reveal the differential mechanisms of ecological benefits influenced by armor structure types and layouts,demonstrate the feasibility of synergistic optimization of ecological and protective functions,and provide a scientific basis for the quantitative design and decision-making of eco-friendly coastal protection engineering.