Since the coast of the Bohai Bay is a typical plain silty one, the problems about engineering sediments, such as fine sediment transportation and how to reduce silting amount for the port and waterway, have come across one after another in the construction of the Tianjin Port and the Huanghua Port of Hebei Province, the two largest artificial ports in China. On the basis of the data observed in situ in the coastal area of the Dakou River in the southwestern Bohai Bay, this paper analyzes comprehensively hydrodynamics, sediment trans-portation, sedimentation of the coastal beach and alluvial and silting evolution, which provide a theoretical basis for the strategic decision of “the shallow water used as the deep water” in the plain silty coast.