The foundation of Tianjin harbor building-repairing base is unstable, the pressure head is high,and the excavation depth of the dockhead reaches 18.2m. This paper describes the stability analysis and excavation implementation of the foundation pit for the dockhead. The practice proves that it is effective to adopt higher construction surface pile follower, dewatering of foundation pits, pieced small -area excavation and timely construction of the upper structure. It may serve as a reference for similar projects.