Water level characteristics change has greatly in the intersection of the Yangtze River and Jialing River before and after the Three Gorges Reservoir.Under the dual influence of inflow and reservoir backwater,this paper uses statistical analysis to study the characteristics of water level before and after the formation of the river.The study shows that the confluence between Jialing River and the Yangtze River is affected by the tributary of the Three Gorges Reservoir,which is estuary characteristics before.The channel segment is affected by the backwater of the Three Gorges Reservoir area to appear reservoir characteristics in the falling and the storage period,but it is estuary characteristics in the flood season.