The status of navigation in the lower Yellow River is introduced. Based on the field data, we analyze the law of the changes which of width, depth, water level and discharge before and after the water and sediment regulation in the lower Yellow River. The results indicate that after the water and sediment regulation, the erosion and broadening of the main channels are obvious, the ability of over-water is enlarged, and the condition of navigation is improved. With the field data from 2001 to 2010 in hydrological stations of Xiaolangdi, Huayuankou , Gaocun, Aishan and Lijin, we build the neural network model which includes water level, discharge and flow area, and the pertinence of the model in every hydrological station is good. The prediction result validates that the water and sediment regulation makes both the width and depth of the main channels in the downstream increase, which is advantageous to navigation.