To better understand the status of fishery resource of Kaozhouyang Bay, we have conducted a seasonal investigation of the community structure and diversity of the nekton by using gill nets and cages net from November 2017 to July 2018. A total of 93 economic species were collected, and among them 61 were fish belonging to 11 orders and 33 families, accounting for 64.52% of the total species number, and the rest were crustaceans. Perciformes (45.16%) and Clupeiformes (7.52%) which were mostly warm water species were the two largest orders of fish. The catches had significant seasonal variation (summer>spring>autumn>winter), and mostly fell in two intervals of 0−8 g and 8−64 g. The diversity indices in Kaozhouyang Bay showed obvious variation. The species richness index was 0.81−3.63; the Shannon-Wiener index was 0.81−2.03; the evenness index was 0.55−1.69. No significant difference was found in the richness index, Shannon-Wiener index and evenness index among different seasons and stations. In conclusion, the total fishery resources in Kaozhouyang Bay are relatively small. The biodiversity shows obvious seasonal variation, while the spatial variation is insignificant.