The processes of water cycle in the middle and lower reaches of the Yellow River change under thecombined effects of climate change and human activities,which impacts flood disaster modes and evolutiontendencies.Status of flood disasters,as well as wet and dry cycle,frequency and intensity of precipitation inthe area are analyzed using Morlet wavelet and trend analysis.The variations of hazard inducing environment,disaster causing factors and vulnerability of hazard bearing body are analyzed in combination with social and economic development,relations between water and sediment and mechanisms of ice floods.Finally,new evolution tendencies of floods are identified:floods in the area will be more serious on the whole,especially in tributaries and small watersheds;floods with low peak discharge may result in heavy losses;and icefloods tend toward mitigation.