Abstract: In light of the beam trawl survey conducted in the Xiamen sea area during April (spring) and November (autumn) of 2021,this study delves into an analysis of the community structure and biodiversity of nekton within this marine region.The findings unveiled a diverse array,encompassing 176 nekton species,categorized into 18 orders,71 families,and 124 genera.This encompassed 107 fish species,18 shrimp species,35 crab species,8 Stomatopoda species,and 8 Cephalopoda species.Regarding the quantitative aspects,the recorded biomass and abundance of nekton were determined as 281.40 kg·km^-2 and 14.49× 10³ ind·km^-2,respectively.Notably,marked spatial and temporal variations were observed across the surveyed stations.Specifically,the resource density exhibited notable disparities,with the eastern waters and Tongan Bay of the Xiamen sea area displaying relatively higher concentrations.Moreover,the resource density in autumn significantly surpassed that in spring.The relative importance index (IRI) highlighted distinct dominant species across the seasons.Parapenaeopsis hardwickii,Parapenaeopsis cultrirostris,and Chiloscyllium plagiosum were dominant during spring,whereas Johnius belengerii and Leiognathus brevirostris took precedence in autumn.These dominant species primarily comprised groups characterized by small individuals,abbreviated life cycles,and comparatively lower nutritional levels.Analysis of nekton indices revealed substantial variability in richness,with relatively significant fluctuations.Conversely,diversity and evenness indices displayed minor alterations.Notably,spring exhibited significantly lower values than autumn,positioning the biodiversity at a moderate level.Furthermore,noteworthy interdecadal alterations in the nekton community structure were evident.Through these observations,this study contributes valuable insights into the dynamic composition,seasonal variations,and structural changes within the nekton community in the Xiamen sea area,offering a comprehensive understanding of its biodiversity and ecological dynamics.