The characteristics of the spatial distribution of plankton in the Oujiang River estuary (27°38′-28°02′N, 120°50′-121°14′E) was investigated in April, 2007. The correlation between the distribution of plankton and nutrients as well as the other hydrological parameters was studied, and the results were presented in the paper. The concentration of suspended particulate (SP), dissolved inorganic phosphorus (DIP) and dissolved inorganic nitrogen (DIN) decreased gradually from the estuary to offshore. The highest concentration of DIP and DIN was detected in the south of Lingqun Island and the southeast of the Oujiang River estuary. However, the growth of phytoplankton was limited by light intensity due to high SP in the estuary. High abundance of phytoplankton was observed outside the estuary as light condition improved because of decreasing SPM concentration. The abundance of zooplankton decreased gradually from the coastal region to offshore and in coincidence with that of phytoplankton. The abundance of macro- and micro-zooplankton was significantly correlated with that of phytoplankton, suggesting the limitation of nutrients and SP on production in the Oujiang River estuary. The coincidence in the distribution of zooplankton and phytoplankton indicates the top-down control of zooplankton on the growth of phytoplankton. We conclude that the ecosystem in the Oujiang River estuary was sustained and stabilized from the interaction between SP, nutrients, phytoplankton and zooplankton in spring.