Base on a project of ship lock in Zhoushan,the structure type of the lock head suitable for over-water construction is analyzed,the corresponding construction technology and water stop measures are put forward,and the foundation treatment method and anti-seepage measures are introduced.Different from integral docking structure of lock head under dry construction condition,the lock head adopts the structure type of combination of prefabricated reinforced concrete caisson and cast-in-site concrete.The caisson is used as the cofferdam.After the caisson is put in place,through the arrangement of temporary and permanent water stops,the caissons of lock head and lock chamber are combined into the overall structure to form dry construction condition.For the rock foundation,the combination of blasting reef and underwater prepacked aggregate concrete is adopted to ensure the stability of the caisson at high tide level.For over-water construction ship lock,the head structure and construction method saves the project cost and shortens the construction period,which is used for reference in design and construction of similar ship lock projects.