Abstract: From August 7 to 9, 2005, a storm tide took place in Diaokou area of the Yellow River estuary as a result of the typhoon matsa. During the same period, field observation on the formation of sediment vertical transporting was carried out on tidal flat. Combining the observation result with the analysis of grain-sizes, a conclusion is drawn that some sediments of fine grain size had transported vertically to the tide flat surface under the loading of storm waves, and the exported sediments mainly consists of very fine silty grains. Furthermore, with the data of pore water pressure measured in-situ, an analysis of this phenomemen has been made on the foundation of the theory of sea bed dynamic response to wave loading.