Based on the analysis of the incoming water and sediment, tide and tidal current characteristics in the Lingdingyang estuary, and combining with four times topographic survey data after phase Ⅲproject of Lingding channel, this paper analyzes the spatial-temporal variation of channel’s siltation amount and slope stability. The results shows that after the transfixion of the 15.5 m dredged channel in Lingdingyang bay, and the flow and sediment process between January 2008 and January 2009 (the channel was not dredged during this period) , the channel’s main tendency was silting-up, but the sedimentation amount was not increased comparing with the previous project (phaseⅠand Ⅱ). The result presents a technical reference for further widening and deepening of the channel in phase Ⅲproject.