According to Guniusha waterway problem and the topographic data of the observed over the past 50 years,this paper analyzed the Guniusha waterway evolution characteristics and the causes of navigation obstacle property and genesis of shallow region.The results show:the main obstruction of Guniusha waterway is due to its transition section wider and shallower.In recent years,the retreat of the Guniusha side foreland is confined by the first phase projects,but the framework of river reach is not changed due to the low elevation of the first phase projects.The water flow in the transition section is scattered,and the channel of flood and dry water is inconsistent,and the first phase projects are not yet fully effective in guiding water flow scoured the transition section of shallow ridge,these phenomena causes the transition section navigation channel become shallower sometimes.In addition,the descending phase of flood becomes shorter after the operation of the TGR,which weakens the erosion rate of the channel,and makes maintaining the 4.5 m waterway depth condition difficult.