This paper took the estuary of Yellow the River which had a high frequency of ocean-earth transformation as the study area.The coastline information was obtained from the interpretation of remote sensing image of 18 years,from 1976 to2002,extracting the mean high tide line as the coastline based on 3S technology.The hydrology characteristics of the lower reaches of the Yellow river and the changes of newly sedimentation land along the coast were analyzed through the matching emendation of the observation time of hydrology data and the imaging time of the images.The results showed:the hydrology characteristics of the lower reaches of the Yellow river were phasic.