On the basis of the data obtained from the investigations on some rivers in China and Australia, the author discusses the spatial and temporal changes of various portions of fluvial-estuarine system during postglacial sea-level rising in present coastal and deltaic areas.The evolution of a fluvial-estuarine system can be divided into four development stages:early transgression, late transgression, stationary and regression.Early transgression brought about filling-in of the paleo-valley formed in low stand of sea level.In response to late transgression the estuaries were created, during the stationary stage the big swamp was developed.The regression led to estuaries to be filled with sediments and then became deltas.At the same locality the fluvial-estuarine system changed with time.In the transgressive period the lower reach of a river changed into an estuary, and then became nearshore area.In the regressive period the nearshore area changed into an estuary, and then became delta.