Based on a series of observation data, experimental results and literature achievements, this paper systematically explores some controversial issues concerning the back-silting phenomenon in the Yangtze estuary deep-water channel, and proposes some new viewpoints of the swale sediment exchange in the mouth bar: 1)The impacts come from three aspects, i.e. temperature, salinity and upstream runoff-sediment conditions, which exists separately but works dependently. These factors have little influence on back-silting of the north deep-water channel; 2)There are several processes related to the back-silting including the mouth bar turbidity zone, high sand content near the bottom, the sediment transport overtopping the north dikes, dam fields siltation, marginal bank slope, river bed compactness, stratification and turbulence effect. They are well consistent but dependently exists, so they can’t influence the siltation independently; 3)The wave action is still the basic dynamical cause of the siltation, which aims at guiding the swale sediment exchange development to the direction of“beach-erosion and channel-siltation”.