Abstract: Under the context of the spatial distribution characteristics and carbon effects of oyster reefs in Haimen, this study aims to explore the influence of Jiangsu Haimen oyster reefs on marine carbon sequestration capacity. A carbon storage estimation model for oyster reefs was established to analyze their spatial distribution patterns and the spatiotemporal variations in carbon storage, as well as to estimate their carbon sequestration potential. The results indicate that oyster reef carbon storage and distribution are influenced by multiple factors, exhibiting significant spatial heterogeneity. Specifically, the distributions of total carbon and inorganic carbon content across layers are relatively uneven, while organic carbon content shows a more uniform distribution. The organic carbon content in the substrate sediments of oyster reefs is relatively balanced, though overall sediment composition fluctuates considerably, exhibiting a vertical drilling trend of decrease-increase-decrease. Based on carbon storage variation methods and field monitoring data, the estimated carbon sequestration capacity of oyster reefs in Jiangsu Haimen is 1.37 kg/m². Oyster reefs significantly enhance marine carbon sequestration through three key processes: calcification, biological assimilation, and biodeposition. Among these, the carbon sequestered via calcification is particularly prominent, offering novel perspectives and methodologies for improving carbon sink capacity in marine ecosystems.