Abstract: Oyster shell reef restoration is an important approach for enhancing the structure and functioning of coastal ecosystems, yet its ecological effects in mangrove wetlands remain insufficiently understood. In this study, we investigated the macrobenthic communities at different stages following the deployment of oyster shell reef (July 2024 to May 2025), using an unvegetated mudflat in the mangrove wetland as a control. By integrating species functional trait analysis, we evaluated the effects of oyster shell reef construction on the functional structure and diversity of macrobenthic communities. The results show that: 1) the oyster shell reef enriches the functional structure of macrobenthic communities in the mangrove wetland, with mudflat communities dominated by infaunal species characterized by burrowing behavior, fragile bodies, and a lack of exoskeletons, whereas oyster shell reef communities are dominated by epifaunal species exhibiting free-living habits, high mobility, and chitinous exoskeletons. 2) The functional structure of oyster shell reef communities exhibits distinct temporal dynamics, shifting from dominance by highly mobile and dorsoventrally compressed pioneer species to more functionally diverse and structurally balanced assemblages. 3) The oyster shell reef significantly increases functional richness (FRic), functional divergence (FDiv), and functional redundancy (FRed), while functional evenness (FEve) and functional dispersion (FDis) show limited changes. 4) FRic and FDiv are strongly driven by species richness, whereas FEve, FDis, and FRed show no significant relationship with species richness.