The south channel in the Yangtze River estuary has always been a good access to the sea with favorable water depth condition. Long series of field data on water, sediment and topography show that a series of regime variations has happened in the south channel, such as scouring in the lower Ruifeng bar and development of central string ditch. Based on the analysis of the recent riverbed evolution characteristics, evolution trend, and siltation characteristics of the 12.5 meters deep water channel of the south channel, we research the regulation strategy of the south channel and put forward the preliminary regulation scheme.