Hengsha east shoal is a large underwater bank located at the east side of Hengsha island.Hengsha east shoal,together with Chongming eastern shoal and Jiuduan shoal are three largest shoals in the Yangtze mouth-bar area.The Hengsha east shoal is an ideal area for port construction because of its stable location and seabed form.A 3-D tidal-sediment model is used to simulate the current dynamics and sediment transport with a dig-in harbor basin built at the Hengsha east shoal.The changes of tidal current and sediment flux before and after the project are compared to analyze the impact of port-building.