The flood and low stage adjustments in downstream reach of reservoir projects have an important effect on water security,water ecology and water resource utilization.The variation features of the water stages are studied in the middle Yangtze River after impoundment of the TGR,based on the hydrological data via one improved method of the time series analysis.The results and con-clusions are as follows:The low water stage exhibited a decreasing trend due to its periodic time increased from 9-14 years to more than 20 years,while the flood stage had no decreasing trend because its change amplitude was less than the max value in history.The main reason for low stage decline is that the erosion amounts in low flow channel increased year by year,when its proportion accounted for the proportion of bank-full channel even reached at 91.5% in 2013.The river resistance has led to flood stage rising which increased by sand coarsening,vegetation coverage in beach above bank-full stage,and other projects such as navigation reg-ulation,revetment,and wharf etc.Change in the water stages is harmful to the improvement of channel depth and the water storage in the reservoir,although the flow discharge compensation of reservoir improves the low flow stage.The water-storage capacities of lakes have no change because the flood stage is not significantly decreased.