There is compelling evidence that river inflow results in considerable inputs of nutrients.It is shown that freshwater outflow to the sea is an important factor which links variations with biological productivity in coastal waters. The Changjiang River Estuary is the breeding and nursery areas for many organisms and it is also the only way of migration for anadromous and catedromous fishes. The estuary is a mixed zone of fresh and sea water,where the environmental factors are varied and complex in the form of seasonal perrodicity. The abiotic(salinity, temperature, runoff and nutrient salt, etc ) and biotic( primary productivity, phytoplankton, zooplankton and necton )environmental features in the Changjiang River Estuary have been shown in this paper. In one year, the values of factors reach the peak in summer and autumn, and lower in winter, pick up in spring. It is shown that there is obvious relationship between the Changjiang River runoff and environmental factors by regression analysis.