Abstract: The authors have systematically analyzed the dynamic, sediment and topographic features of the Miaodao Strait,and then studied the channel effect and its dynamic topographical expressions including strait formation and evolution, tidal current convergence and divergence, erosion and deposition, difference of the flood and ebb tidal currents and the formation of the Dengzhou shoal, the channel sand transport and its sediment effects. According to the study results we know that the strait channel was formed with the gradual rise of then relative sea level since late Pleistocene.The modern Miaodao Strait and its dynamic system came into being during 5 000~6 000 aBP and then entered the modern development stage of the strait geomorphology.The Miaodao Strait has obvious strait effect.When flood current from west and ebb current from east flow through the E-W strait that opens westwards,the current speed changes with the area of the strait section.The central part of the strait experiences the largest erosion,and the erosion decreases with the increase of width of the strait and turns into accumulation.Silt from seabed of the strait and the nearby coast becomes the direct source of muddy area along the coast of the Yellow Sea in the north of the Shandony Peninsula.