Advances in ecological studies on estuarine zooplankton are reviewed on the domestic and abroad published papers. This paper includes estuarine zooplankton species composition, spatial and temporal distribution, biomass and the reviews of the effects of the environmental factors. Estuaries are tidally-influenced ecological systems. Fluctuations of environmental factors are more significant and complex in the systems due to the combination of fresh water and salt water, land and ocean influences. As a result, the study of the spatial and temporal variability of estuarine zooplankton communities is very important for a better understanding of the functioning of coastal ecosystems. Estuaries comprise extreme environments for zooplankton development. Typically, the most abundant groups of zooplankton are protozoans, rotifers, copepods, mysids and medusas. Environmental parameters and anthropogenic impacts play major roles in determining spatial and temporal patterns of zooplankton distribution and species composition. Variability is mainly caused by food, temperature, salinity, herbivory and riverflow. The fluctuation in salinity is tightly correlated with distribution of zooplankton. The influx of freshwater into the estuary has a dramatic impact on the community structure. The microzooplankton－protozoans, rotifers and copepod nauplii－plays a significant role in estuarine ecosystem. Microzooplankton represents a key link in the microbial food web and the traditional food web. Any attempt to determine the relative abundance of zooplankton groups, must be based on collections obtained using a plankton net with an appropriate mesh size. For example, many Chinese scientists use the plankton net Ⅰor Ⅱ (mesh size 507 and 169 μm)to collect zooplankton samples. This was lead to serious underestimates of the smaller components of the zooplankton(e.g. copepod nauplii) which constitute an important component of the diet of larval fishes. Additionally some ideas for further studies on estuarine zooplankton in China are proposed.