Due to river runoff flow and tidal flow, coastal waters are often characteristic of high concentration of suspended sediment. In this paper, by using MODIS images of 250 m resolution and hydrodynamic model and in site observation, the author analyze the distribution characteristics of suspended sediment and hydrodynamics mechanism. Relatively high Suspended sediment concentration distribute in the alongshore and south and north of Nanhui neareshore. During the flood tide period, distribution range of high suspended sediment concentration is northward moved. During ebb tide period, the zone of turbidity maximum is shown near the south of Nanhui nearshore. Based on terrain data analyses in 1999, 2003 and 2008, altitude value of underwater terrain in most area of Nanhui nearshore is increase. Most area of Nanhui nearshore is depositing. Momaosha mudflat in the north of Nanhui nearshore is extending southeastward. South of the Nanhui subaqueous beach is extending slowly southeastward and southward.