Jiaozhou Bay is a temperate semi-closed bay in the Yellow Sea, located in the Shandong Province, along the northern coast of China. In order to understand the characteristics of fish community structure in Jiaozhou Bay, data from four bottom trawl surveys (2016-2017) were used to analyze the variations in fish species composition and species diversity of fish communities by using the means of relative importance index, ecological diversity indices, canonical correspondence analysis, and non-metric multidimensional scaling. The results showed that a total of 46 fish species were captured, which belonged to 2 classes, 14 orders, 53 families, and 84 genera. Among them, Osteichthyes fishes with 45 species were the dominant one, accounting for 97.83% of the total fishes. Of these, the Perciformes fishes were the most dominant group, in which 22 species in 19 genera and 13 families were observed, which accounted for 47.83%, and followed by the Scorpaeniformes fishes with 7 species in 7 genera and 6 families, accounting for 15.22%. The seasonal variations in the number of fish species were obvious, with the highest being in summer with 23 species and the lowest in autumn with 16 species. The fishes in Jiaozhou Bay belonged to temperate fauna, which was dominated by the warm temperate fishes (47.83%), and followed by warm water fishes (30.43%). Cold temperate fishes, which were the least abundant one (21.74%). The predominant species of fish communities included Thryssa kammalensis, Sebastiscus marmoratus, Paralichthys olivaceus, Hexagrammos otakii, Sebastes schlegelii, and Chaeturichthys stigmatias. The diversity analysis showed that there were significant seasonal variations in fish species diversity. The values of Shannon-Wiener diversity index (H') ranged from 1.668 to 2.453 with an average of 2.031, the highest was in summer and the lowest in spring. The values of Pielou evenness index (J') ranged from 0.577 to 0.808 with an average of 0.687, with the highest value reorded in autumn and the lowest in spring. The values of Margalef richness index (D') ranged from 2.431 to 3.123 with an average of 2.824, the highest was in winter and the lowest in autumn. The Canonical Correspondence Analysis (CCA) revealed that pH, dissolved oxygen (DO), water temperature, and water depth were the most important environmental factors affecting the species composition of fish communities in Jiaozhou Bay. Water temperature and pH were the main factors affecting both spatial and temporal changes in fish community structure and diversity. Compared with the historical survey data, the community structure of fish had changed greatly due to disturbances from anthropogenic activities in Jiaozhou Bay ecosystem. These changes included changes in the species diversity level with a reduction in the number of species, and a significant change in the composition of the dominant species, suggesting that a simplification of fish community structure has resulted in this bay.