Abstract: The Yangtze Estuary is one of the most typical hypoxic regions in the world. The aggravation and expansion of the hypoxia are obvious in the past few years. This paper aims to synthetically analyze the origin of the hypoxia, its biogeochemical processes and its hazardous influence on the local ecological system. By comparing with other hypoxic areas in the world, the hypoxia of the Yangtze Estuary is found rather different geographically and oceanographically from those in the Gulf of Mexico, the Baltic Sea, the Black Sea and Tokyo Bay. The study of the case would greatly help the deeper research of marine ecology in this area. By briefly combining geochemistry, ecology, oceanography and other subjects, the necessity of developing hypoxia ecology is proposed by the authors to fill the blank in this field.