The data series of rainfall, runoff and flood at the main sites or reaches in the Yellow River basin were extended upto 2010 and its changing characteristics were analyzed. Based on the runoff reduction, the influence of the underlying surfacechange on the consistency of hydrological data series were analyzed through the relationship change between rainfall and runoff. Bytaking consistency treatment with different methods, this paper proposed 3 runoff series in different underlying surface stages, andthe design runoff result of underlying surface stage I was recommended. The natural design flood of Yellow River basin and thedesign flood occurred every 5 years or below of recent stage II underlying surface in the middle reaches were presented byanalyzing the influencing factors of the flood consistency, taking reduction of the main influencing factors and the influencingfactors of frequent flood magnitude in the middle and lower reaches in the Yellow River.