Abstract: Dynamic changes of surface sediment (SS) of the estuary turbidity maximum zone (TMZ) largely reflect the exchange process between suspended and bedload sediment under river-tide interaction, which directly relates to sandbar regulation within the TMZ. Based on hourly hydrological data for 9 days and analytical data for surface sediment samples collected in June 2013 that cover a continuous neap-spring tide cycle, this study analyzed the sedimentary dynamic process of SS of the TMZ within the South Passage, Changjiang Estuary. The results show that SS of the TMZ along the South Passage is relative fine with silt being the dominant size fraction and is characterized by poor sorting. Average grain size, sorting coefficient and skewness coefficient of the SS all decrease gradually from neap tide to spring tide. SS is fine, and is composed largely of very fine silt because of flocculating settling of suspended sediment during the ebb tide. SS during the flood tide, however, is relative coursing because of the sedimentation of coarse fine sand under the support action of rising tide. The sediment component of SS exhibits two changing modes. The main mode is fine suspended sediment sedimentation under tidal forcing and saltwater flocculation, which is dominated by coarse clay and very fine silt. The secondary mode is fine particle sediment erosion due to riverine discharge, which increase the proportion of fine sand and result in SS coursing mainly in terms of medium silt. Fluvial discharge dominates the short-term variation of SS, while salinity change controls the overall thickness conversion of SS.