The main processes of interaction between the coastal water, shelf water and Kuroshiowater in the Huanghai Sea (HS) and East China Sea (ECS) are analyzed based on the observation andstudy results in recent years. These processes include the intrusion of the Kuroshio water into the shelfarea of the ECS, the entrainment of the shelf water into the Kuroshio, the seasonal process in the south-em shelf area of the ECS controlled alternatively by the Taiwan Strait water and the Kuroshio water in-truding into the shelf area, the interaction between the Kuroshio branch water, shelf mixed water andmodified coastal water in the northeastern ECS, the water-exchange between the HS and ECS and thespread of the Changjiang diluted water.