Abstract: Zooplanktons, which are secondary producers in oceans, are essential for maintaining the abundance of fishery resources and marine ecological balance. To explore the spatial distribution characteristics of zooplankton and relationships with environmental factors in the northwest Indian Ocean, we analyzed the species, abundance and dominant species composition. Redundancy analysis model (RDA) was used to analyze the relationship between the environmental factors and the dominant species. Results shown that a total of 241 species belonged to 129 genera from seven phyla, including undefined species. The most dominant group of zooplankton was Copepoda (108 species). The total species and average abundance gradually decreased with increasing water depth. Distribution of the average number of species, total number of species and average abundance relatively balanced in terms of longitude. The average abundance decreased with increasing latitude. The dominant species groups were mainly Copepods, Ostracods and Chaetognaths, and the average abundance of dominant species gradually decreased with increasing water depth. Deepwater species were distributed in all stations basically. The number of deepwater species at stations at latitudes of 2.5°N−5.5°N were relatively richer, while the total abundance of deepwater species at stations at latitudes of 0.5°N−1.5°N were relatively higher. Deepwater species had an indicative effect on upwelling in this area. The main environmental factors affecting the distribution of dominant species were temperature, inorganic nitrogen and chlorophyll a.