Abstract: The water pollution of ecosystems in river mouths, deltas, wetlando and their adjacent seas is a common concern of the world. Excess inorganic nutrients or organic matters, waste, toxic substances, pathogens carried by land runoff and sewage pour into the delta estuary and coastal waters, that cause eutrophication, hazardous elements or pathogen contamination, and deterioration of the ecosystems ecosystem. This article reviewed the causes and consequences of water pollution in the ecosystems, and countermeasures are proposed for consideration.