The Yellow River erosion effect was evident after the retaining operation and flow-sediment regulating operation of Xiaolangdi Reservoir, the discharge capacity was improved obviously. The main factor influenced the erosion efficiency was hydraulic factor (V-3/h), bed load grain size and suspended load grain size, and bed coarseness. The ultimate effect of all above factors was the development erosion condition, so we choose the previous cumulate erosion volume as the influence of above factor. Based on the observed data of the retaining operation of Xiaolangdi and Sanmenxia Reservoir, we analyze the erosion efficiency of different discharge. Results show that, the erosion efficiency was improved with the increasing of the discharge, and the previous cumulate erosion volume was the factor at the same time. In the same discharge, the erosion efficiency was decreased with the increasing of the previous cumulate erosion volume, when the discharge was larger than 4000m(3)/s, the previous cumulate erosion volume was also influenced the erosion efficiency, but the effect was reduced than the discharge was smaller than 4000m(3)/s.
