Abstract: Based on the four-season survey data of macrobenthos in Xinghua Bay from 2020 to 2021, combined with historical data for comparative analysis, this paper discussed the community structure characteristics, spatial and temporal dynamics of macrobenthos in this sea area and the effects from environmental changes. Results show that a total of 253 species of macrobenthos belonging to 11 phyla were collected in four seasonal cruises, of which annelids (106 species), arthropods (69 species) and mollusks (45 species) were the main groups. Phyllophorus hypsipyrga and Protankyra bidentata were the dominant species, while Lumbrineris sp., Aglaophamus dibranchis and Neoxenophthalmus obscurus were the important species. The average abundance was (212±25) ind/m², with polychaetes absolutely dominant; and the average biomass was (34.37±30.99) g/m², echinoderms were dominant. The average abundance and biomass of the stations in Xinghua bay were slightly higher than those in the middle and mouth of the bay. The comparative analysis showed that the species and quantity of macrobenthos in this sea area fluctuated to a certain extent. Small sediment feeders and detritus feeders such as annelids, arthropods and echinoderms gradually became the main body of the community. The miniaturization trend of the community may be related to the intense human interference in the sea area. There was no significant difference in the community structure between the power plant drainage station and other stations, and even there was a high abundance during the summer period, which may be related to the richness of organic debris in the thermal discharge and the limited influence of the stratification of the thermal discharge on the bottom surface, especially the organisms within the bottom. Due to the lack of long-term continuous data support, the comprehensive impact, long-term cumulative effect and mechanism of thermal discharge need to be further explored.