Abstract: In recent years, incidents of marine bio-invasions have increasingly threatened the safety of cooling water system at coastal nuclear power plants (NPPs). In order to assess the biological profile of the sea area around a NPP, a year-long survey was conducted from September 2022 to August 2023. We identified a total of 211 species belonging to 10 classes of marine organisms, with chordates and crustaceans emerging as dominant species. Biomass exhibited two peaks, notably in May and late July to early August. Risky species included Acetes chinensis, Pseudeuphausia sinica, Engraulis japonicus, and Pleurobrachia globosa, etc. Here, we also analyzed the factors contributing to the surges of Engraulis japonicus and Acetes chinensis around cooling water intake. It was determined that the biological risk period for the cooling water system spans from April to September. These findings are instrumental in refining early warning and prevention systems against biological disasters at NPPs.