The sea area near the Ma'an Islands in Shengsi has complex natural conditions and is a spawning ground, feeding ground, and migration channel for many fishes and crustaceans. In order to study the effects of environmental factors, seasonal fishing suspension and other factors on the seasonal dynamic succession of fish and crustacean community structure, based on the survey data of fish and crustacean swimmers in the adjacent waters of Shengsi Ma'an Islands in Zhejiang Province in four quarters of 2021, this study employed One-Way analysis of variance (ANOVA), similarity percentage analysis (SIMPER) and non-parametric multivariate analysis of variance (PERMANOVA) to study the seasonal changes of the average resource density and average individual size of the two groups. RDA analysis was used to study the relationship between seasonal fishing bans and environmental changes and the two taxa and their dominant species. The results showed that a total of 103 species were caught, including 53 species of fish, 50 species of crustaceans, 5 species of dominant species (Harpadon nehereus, Coilia mystus, Trichiurus lepturus, Larimichthys polyactis and Collichthys lucidus), and 3 species of crustaceans (Oratosquilla oratoria, Portunustri tuberculatus, and Charybdis japonica). There were significant seasonal differences in the community structure composition of fish and crustaceans (average resource density and individual size), but there were no significant regional differences. The average density of fish and crustaceans increased from spring to autumn and then slowly decreased in winter, whereas the average individual size was the smallest in spring and larger in other seasons, especially in summer. The results of the RDA analysis showed that fishing pressure was the main factor that significantly affected the seasonal variation of average resource density and average individual size of fish and crustaceans (RDA1), and the seasonal variation in the functional characteristics of fish and crustaceans was closely related to fishing pressure and environmental factors caused by fishing bans. This study shows that fishing bans and environmental factors have a significant impact on the functional characteristics (number and individual size) of fishery ecosystems, and further research on long-term changes in functional characteristics needs to be conducted. The results of this study can provide scientific basis and reference for the evaluation of marine protected areas and the sustainable utilization of fishery resources.