Jingtang Port is the first deep-water port built on the sandy-silty coast in China. Since its completion in 1992,there have been many times of sudden siltation in channel. In order to master the mechanism of sudden siltation and summarize the experience of building a port on the sandy-silty coast,we analyze the coastal dynamic conditions and characteristics of the sudden siltation in channel,and point out that there is a wide surf zone and “generalized littoral transport zone” under the strong wind waves. The main reason of channel’s sudden-siltation is the strong wind waves in autumn and winter,which move and transport the silty sediment in offshore area. It is the key to estimate the sudden siltation in the channel of silty beach to master the movement law of silty beach sediment under strong wind waves,especially the characteristics of high concentration of bottom layer. The research results may serve as reference for the site selection of port construction at sandy-silty beach and the construction of sand retaining dike.