Abstract: The characteristics of suspended sediments in an estuary are important not only for the research of sediment transportation and deposition, but also for the geomorphological study of the estuarine zone. Based on the data acquired from the in-situ observation in August, 2008, we processed the ADP data and analyzed the grain size of the suspended matter. The variation in suspended sediment was studied in a temporal and spatial framework. The results show that the suspended sediment concentration (SSC) varies not only with the alternation of flood and ebb tides, but also with the alternation of spring and neap tides. The maximum SSC usually appears during the flood peak in general. The SSC is higher in neap tide instead of spring tide.The suspended sediment is mainly composed of muddy silt and remains the same in different tidal cycles.The SSC mainly depends on current speed but not on grain size.