This study aimed to investigate the community characteristics of major nekton based on the catch survey data from Yiwan Bay of Taizhou (27.9°N-28.6°N and 121.1°E-121.9°E) in October 2016 and April 2017, through analysis of functional groups along with the niche of and probability of interspecific encounter (PIE) between species. The results showed that there were 13 and 11 species of major nekton in spring and autumn, respectively, most of which were the short-distance migratory species or settler species, with low seasonal turnover rates. In addition, the benthivores/piscivores feeding functional group (FG4) was dominant among the major nekton in spring and autumn, with low trophic levels. Additionally, the total PIE between the major nekton in spring and autumn were 0.66 and 0.76, respectively, and that in autumn was higher than that in spring. There were significant differences in the niche breadth, both in spring and autumn. Specifically, there were four broad niche species, seven meso niche species, and two narrow niche species in spring; conversely, there were five broad niche species, four meso niche species, and two narrow niche species in autumn. In addition, the niche breadth (Portunus trituberculatus) was associated with the highest PIE and maximum niche breadth in both seasons, along with the strongest abilities of competition and resource utilization. Moreover, the interspecies niche overlap values in spring and autumn were 0.14-0.88 and 0.21-0.91, respectively, indicating uneven degrees of interspecies overlap in the two seasons. In summary, small seasonal variation was observed in the composition of major nekton in the studied sea area, and a single functional group had taken the dominant place, most of which belonged to the low and middle trophic species, with a large niche breadth and PIE. Thus, this might result in the fluctuations in community numbers, as well as a decline in the structure and functional stability of the communities.