Abstract: With the rapid development of global offshore wind power industry, the impact of offshore wind farm (OWF) on marine ecosystem has received a widespread attention. By selecting the Bozhong offshore wind farm and its adjacent waters as the research object, the changes in water quality and sediment quality indices, as well as in community structures and diversity indices of planktons, benthonic organisms and necton in the waters of wind farm site before the construction of wind farm and after its official operation are compared and analyzed by using the data obtained during the ecological environment surveys carried out in the wind farm site watwes and its adjacient sea areas before the wind farm construction (April 2019) and after its official operation (May 2024). And the influences of offshore wind farms on marine ecological environment are evaluated comprehensively. The results show that the water quality in the Bozhong offshore wind farm and its adjacent waters has a trend of improvement after the official operation of the wind farm. Compared with the situation before the construction of the wind farm, the propotions of dissolved inorganic nitrogen (DIN), plumbum (Pb) and mercury (Hg) concentrations exceeding Class I water quality standards have decreased by 45.7%, 22.5% and 6.8% respectively and the surface sediment concentrations all meet the sediment quality standards of Class I. The average content of copper, however, increases by 9.4% in water and 52.2% in sediment after the wind farm operation. This should be observed as a key indicator for long-term monitoring. Aafter the official operation of the wind farm, moreover, the abundance of phytoplankton and the biomass of zooplankton and benthos decrease by 16.9%, 64.5% and 20.0% respectively, while the species number, diversity index and richness index of the plankton community increase significantly, indicating that the community stability of phytoplankton enhances, the community stability of zooplankton improves, the community stability of benthos deteriorates and the dominance of polychaeta which has smaller individual size and higher tolerance to environmental change becomes more obvious. Meanwhile, the artificial fish reef effect generated by the foundation structure of the offshore wind farm leads to an addition of fish with tactile characteristics among the dominant fish species. The fish catch volume has increased by 6.6% (in the mass) and 30.3% (in the length) after the operation of the wind farm. This study can provide a theoretical basis for the construction of intelligent supervision system of offshore wind farm ecosystems and offer technical support for the supervision of the whole life cycle and the entire chain ecological environment for offshore wind farms.