Abstract: The navigation channel of Lujiahe Shallow Reach of the Yangtze River is divided into two:sand channel and gravel channel by the channel bar named "qiba".The incoming condition of this reach including flow and sediment has a significant effect on thefluvial process of the navigation channel.Based on the field data and model experiments of moveable bed,the effect of process of the discharge on scouring of the sand channel after the flood peak has been analyzed.It has been found that the sediment deposited in thesand channel during the flood season will be scoured when the flow discharge keeps in the range of 10000～25 000 m³/s.After the construction of the Three Gorges Project,the incoming condition of flow and sediment in this reach will change greatly,in which the duration of the flow discharge keeping in the range of 10 000～25 000 m³/s will increased to some extent,therefore the phenomenon of temporary cutt-off of the navigation channel will be improved.