The main objective of this paper is to discusses the problems of sea water intrusion and its effect on eco-environment in the coastal area of Yellow Sea and Bohai Sea.Sea water intrusion has been discovered since 1970's at some places of the coastal area of Yellow Sea and Bohai Sea, and it is extending very fast towards inland and is very heavy.It has caused under-ground water quality deterioration and short supply of fresh water at some places. It has re-sulted in the decrease of land productive capacity, ...