Abstract: The running of Danjiangkou Reservoir has changed the characteristics of original water sediment condition of Hanjiang River, the downstream river bed of the reservoir has been caused scouring. The enhanced Danjiangkou Dam is the water source project of the midroute of South North Water Transfer Project. The water in the reservoir over the spillway crest will result in very high velocity, and thus affect downstream river bed, water resources supply and ecoenvironment after the project operation. In order to contrast with the project operated, a river channel geomorphologic map with a scale of 1∶10 000 from Danjiangkou to Nianpanshan of the dam downstream reaches was made in 2005. From the information over the years, there occurred great amount scouring to different extents from Danjiangkou to Nianpanshan. The calculated result indicates that the scouring intensity changes with time and distance from the dam site and is related to the inflow rate.