Abstract: Based on the data (including tidal current, suspended sediment concentration, and salinity) obtained from fixed-point observation at Yangtze River estuary during the dry season and tide period in 2013; and through the analysis on impacts of the salt water intrusion on flow structure and sediment movement, a study was conducted on the salt-fresh water mixing and suspended sediment transportation in North passage of the Yangtze River estuary. The results show that during the observation period, north passage was under the influence of salinity gradient both horizontally and vertically in some degrees; during the ebb and flow, vertical velocity no longer follows the distribution patterns of tideless river. The flow structure in estuary changed, creating an estuarine water circulation in that the upper water flowing out to the sea whereas the bottom water flowing back to the upstream. Under influences of multiple factors, especially the obstruction to the sediment discharge due to estuarine water circulation that it is favorable to the bottom sediment movement to upstream, so the circulation results in the phenomenon of upper sediment flowing out to the sea and bottom sediment moving back to the upstream. In different river sections, vertical net circulation transports sediment back to the upstream, but much more sediment is transported to the sea under the influence of advection and tidal pumping action, as a result, in the observation periods, net transport volume of the suspended-sediment is to the sea.