The deep-water channel at north passage of the Yangtze Estuary serves as the exclusive waterway for heavily laden large vessels accessing Shanghai Port and ports along the Yangtze River.In view of the frequent loss of control of large inbound vessels at the eastern end of the North Passage,a three-dimensional tidal current numerical simulation method is adopted to analyze the hydrodynamic causes for the loss of control of large inbound vessels.The results indicate that the sudden increase in cross-currents at the navigational channel caused by tidal reversal and the constraints of local construction boundary is one of the main reasons for the vessel loss of control at the eastern end of the North Passage.During the flood-to-ebb transition period,the ebb current that first starts ebbing at the South Passage Estuary flows around the head of the South Dike and impinges on the channel of North Passage,resulting in a sudden increase in the cross-current in the eastern end of the North Passage.During the ebb-to-flood transition period,the flood current-currents around the head of the North Dike into the North Passage,leading to an increase in the cross-current in the waterway at the eastern end of the North Passage.Recently,the Extension Project of Hengsha Avenue may further intensify cross-current effects at the eastern end of the North Passage during the the ebb-to-flood transition period,which needs to be taken seriously.The above research results provide research support for ensuring the navigation safety of the North Passage and offer a reference for promoting the application of numerical simulation technology in navigation safety management.