This paper expounds the project′s background and seeks the measure to replace the original approach of storing clear water and releasing muddy flow in Xiaolangdi reservoir,so as to lower the Tongguan elevation and to reduce the flood disasters in the Weiluohe river′s lower reaches.Analysis shows that in Tongguan reach,bed elevation increases when scouring occurs in the upper reach at low temperature,and bed elevation declines when silting occurs in the upper reach at high temperature.Both situatious would transport a lot of silt to the lower reaches.Authors deal with the layout and optimization of flushing gallery by analyzing two examples.One is the drop of Sanmenxia Reservoir level which causes headcut scour,and the other is drawing water from the Yellow River to Donglei to lower the bed elevation.The project of using the flushing gallery in Sanmenxia to lower the Tongguan elevation would intercept coarse sands before entering Xiaolangdi reservoir so as to lower the Tongguan elevation and increase Sanmenxia reservoir′s total storage.