Abstract: The recent studies show that the water channels and sandbanks in radial sandbank of South Yellow Sea (SYS) have been gradually migrating southward.Hydrodynamic analysis on the mechanism of such evolvement trends is thus crucial for the regional development in the coastal zones of Northern Jiangsu province.In this study,the staged evolution of coastlines and seabed topographies since the northern retrieval of the Yellow River estuary is first studied,and a numerical tidal wave model is then established to investigate the hydrodynamic characteristics of the tidal wave system in SYS and evolutions of the Yellow River delta in the different stages.The results show that because of the coastal zone erosions and vanishing of the delta formed by the abandoned Yellow River estuary in Northern Jiangsu province,both tidal elevation and hydrodynamic condition in radial sandbank of SYS have been strengthened,and the strengthened regions are found to be gradually migrating southward.The large-scale southward regional reinforcement of dynamic axis of flow is likely to be one of the major contributing factors causing the entire sandbar regions of SYS migrating southward.