Abstract: With the model test,this paper researches overbank flood sediment concentration and its gradation change rules from Jahe beach to Gao village river section of lower Yellow River.The test shows that: Firstly,the more overbank sediment laden flow sediment concentration the main channels have,the more differences they gets.Secondly,on the beach area,the less the sediment concentration becomes,the larger the attenuation range inside of dike and of beach surface becomes.At the same,the sediment particles of overbank sediment laden flow has the screening function obviously during the silting process.Thirdly,the smaller the river peak flow becomes,the more quickly the sediment concentration attenuates along Ertan.