During dock construction in sandy site, the dewatering of dock foundation pit affects the displacement of sheet-pile wharf nearby. It can even appear the phenomenon that the sheet pile wall moves to the shore side. Based on a new shipyard project in Singapore, this paper presents the analysis and research for the results of the sheet pile wall displacement monitoring during the dewatering work, and also presents numerical simulation by the application of finite element program PLAXIS. The result of numerical simulation further verifies the correctness of the results of displacement monitoring.