After the impoundment of the Three Gorges project,riverbed of the sandy gravel reach of Yichang-Dabujie had been eroding continuously,and water level in the same discharge dropped gradually in the dry season.Based on the real-measured data,this paper probes into the reason for the water level’s dropping in the dry reason and its effects on the navigation condition.It is concluded that riverbed erosion is the main reason for water level’s dropping in the dry season. With the further dropping of the water lever in the dry season,to ensure the operation of Gezhouba navigation lock,the navigation lock dispatch pressure would increase,and navigation obstruction problem in local pebble shoal would turn more serious.