Foraminiferal assemblages were analyzed at Core DT from the Chongming Island, Yangtze River Estuary. Five foraminiferal assemblages were recognized since 13 ka B.P.. Integrating the sedimentological and magnetic characters, the authors established the evolution of hydrodynamic conditions in Chongming Island. The tidal current were enhanced from the foraminiferal assemblages 1 to 4, but reduced from assemblages 4 to 5. The foraminiferal assemblages in Core DT reveal a history from the shallow sea, shallow sea-river estuary, delta front-prodelta, sand bar estuaries, to supratidal zone over the last 13 kyrs.