The development and evolution of the estuary and coastal zone depend upon the dynamic processes of rivers, tides, waves, and littoral currents,etc. Chemical sedimentation and biological processes are also at work, but the dynamic processes are the most important. Human activities including Coastal engineering, industrial and agricultural pollution and improper fishery may contribute great effects to the modification. The modern estuary and Coastal zone results from the interrelation and interaction between various natural processes and human activities. It is a special physical geosystem affected by both continental and oceanic factors. The geosystem may be classified into four specific systems: dynamic system, environmental quality system,natural resource system and ecosystem. In the geosystem the ecosystem is an organic system whose limits coincide with those of the former. The upper limit of the coastal zone may be determined by the uppermost reach of the forces of tides, currents and waves as expressed by their erosion and accumulation, while the lower limit is defined by the reach of con-tinental physical and chemical processes indicated by river discharge, as well as by pollution. The estuary and coastal zone is not only a special geosystem but a special ecosystem as well. The limits of the coastal zone tally compara-tively with the differentiation of the regional geographical complex and meet the needs of the comprehensive development of the coastal zone resources. The geosystem and ecosystem of the estuary and coastal zone have two properties:first, the processes proceed rapidly; secondly, the processes may be disturbed by human activities, the latter being more important. Hence the study of the influence of human activities on the geosystem structure and the ecolo-gical balance is an urgent task.