Zooplankton are important food organism in the marine ecosystem, and its community structure and population distribution reflect the productivity of the waters. In order to understand the interspecific relationship of the zooplankton community and the impact of changes in environmental factors on the niche differentiation of dominant species in the Bailanzi waters, basing on the zooplankton survey data in March and December of 2022 and June of 2023, we obtained the dominance index of zooplankton in this sea area through calculating the Levins niche width value and Pianka niche overlap value of the dominant species, and divided the niche types of the dominant species into broad niche species, medium niche species and narrow niche species. The redundancy analysis method was used to explore the main environmental factors affecting the niche differentiation of dominant species of zooplankton in Bailanzi waters. The results showed that there were 9 dominant species and all of them were wide ecological niche species in March 2022, 5 dominant species and all of them were wide ecological niche species in December 2022, and 6 dominant species, including 3 wide ecological niche species and 3 narrow ecological niche species, in June 2023. The niche overlap indexes of the dominant zooplankton species in March 2022 ranged from 0.54 to 1.00, and those in December 2022 ranged from 0.60-0.98 in March 2022, 0.62-0.99 in December 2022, and 0.62-0.99 in June 2023. Redundancy analysis showed that the main environmental factors affecting zooplankton distribution are temperature and salinity, followed by pH, dissolved oxygen (DO), ammonia nitrogen (NH₃-N), dissolved inorganic phosphorus (DIP), dissolved inorganic nitrogen (DIN), chemical oxygen demand (COD). The research results are expected to provide basic information for an in-depth understanding of the interspecific relationships of zooplankton communities in Bailanzi waters and the adaptation mechanism of zooplankton to environmental changes, and provide a theoretical reference for high-quality marine ranch construction in this waters.