Abstract: Flood disaster of Weihe river in 2003 was caused by many factors, such as the loss of serious water and soil erosion in upper and middle reaches of the river, increased mud coming into the river and a large amount of silt sedimentation which ran up the riverbed in lower reaches of the river, and the bad quality of dike in south mountain branch and imperfect drainage system. Because of the large amount of mud sedimentation, variable water lever, lower criterion of south mountain branch dike and growing flood disaster, much measures should be taken to prevent flood disaster, such as the comprehensive way to control the loss of water and soil erosion in the whole watershed of Weihe river, making higher and reinforcing the leve of Weihe river and the dike of south mountain branch, strengthening the repairing project of the riverway.