We analyzed the spatial and temporal patterns of crustacean communities based on bottom trawl samples of four seasons from 2020 to 2021 in order to investigate the effects of changeable marine environment and high spatial heterogeneity on biological communities in the coastal islands at the local scale. Multivariate statistical methods were employed including hierarchical clustering and non-metric multidimensional scaling (NMDS). Environmental factors such as temperature, salinity, and depth were investigated simultaneously to resolve the influencing factors using redundancy analysis (RDA), while community stability was assessed using abundance biomass curves (ABC) and W-statistics. A total of 53 species of crustacean were collected, belonging to 29 genera, 13 families, and 2 orders, with shrimps accounting for 56.06% of the total species number. There were 43 species found in the autumn, followed by 41 species in the winter, 31 species in the spring, and 26 species in the summer. The seasonal changes of the dominant species were obvious. In summer and autumn, the dominant species were medium- and large-sized economic species, such as Parapenaeopsis hardwickii, Solenocera crassicornis, and Portunus trituberculatus, whereas small individual bait species like Charybdis bimaculata and Parapenaeopsis tenella dominated in the winter and spring. Oratosquilla oratotria was revealed as the only dominant species in common in the four seasons. The density of crustacean resources fluctuated dramatically throughout the year, with an uneven spatial distribution, peaking in autumn and declining in spring, and the highly significant higher in summer and autumn than in winter and spring (P<0.001), with the highest resource density in the near rocky reef area and the smallest in the shallow water area on the estuary side. Affected by the migration and selective distribution of seasonal migratory species, as well as the regional differentiation of the hydrological environment in the reef system, the crustacean community structure had significantly seasonal changes and regional differences, forming a pattern of high heterogeneity in summer and autumn, high similarity in winter and spring, and outstanding differentiation between shallow and deep water areas on the estuary side and the outer side. Environmental factors such as bottom water temperature, bottom salinity, bottom dissolved oxygen, and water depth were significantly correlated to community structure heterogeneity. The ABC curve showed that the crustacean community was stable and had a strong tolerance to disturbance. This study demonstrated that the dominant crustacean resources in the sea area around Dachen Island had a clear seasonal cycle, and varied in community structure in different regions on the local scale, but they all maintained high levels of resources, which played a positive role in the maintenance of local fishery resources and provided a resource basis for the functional design of local marine ranching.