Based on the analysis of the water and sediment variation at Wuzhou station form 1955 to 2010 and the river bed deformation below Changzhou dam from 2002 to 2011, it is concluded that the runoff change was relatively stable, but the river sediment experienced three periods, and the sediment discharge and sediment concentration decreased sharply after 2003. Though the change happened before and after the construction of the Changzhou dam, the Changzhou dam was not the main reason for the decreased sediment concentration. And the dramatic deformation below Changzhou dam was more possibly caused by sand mining and channel regulation.