To deeply understand the complex changes of low water regime in the middle and lower reaches of the Yangtze River,the monthly variation characteristics of low water level at Yichang,Shashi,Hankou,Datong and other important control stations were studied by using the hydrological variation diagnosis system.The results show that the variation of Yichang station in dry season was moderate and strong.Strong and huge variation occurred in Shashi station,and the variation degree was the strongest.Pure random (no variation) to strong variation occurred in Hankou station;Pure random (no variation) to medium variation occurred in Datong station.Each station experienced downward variation from October to November.The water level (discharge) of Yichang,Shashi and Hankou stations decreased by 0.76 m(6 000 m3s),2.82 m(7 000 m3s) and 1.66 m (10,000 m3s) respectively after the flood season in 2021 compared with 2003,However,there was no obvious changes at Datong station,and its potential impact on shipping should be further analyzed.