The highest water level of the lower reaches of the Yangtze River in the area of Jiangsu Province is continuously higher and its duration is obviously longer than before during the last decade. Therefore, the flood control became heavier and heavier, the regulation of the Yangtze River is payed the important attention by central and local government. In the paper, the heavy flood in 1998 is compared with that in 1954, based on data of practical measurements of Datong Hydrologic Station in the main channel and others in its down stream. The variable regularities of the average flood volume, mean of the highest water level, mean of the highest water and the average days when the water level is over the warning water level for flood control in down stream from the 1960s to the 1990s are discussed. Through the analysis of such factors as the water volume from upper and middle reaches of the Yangtze River, the tide from East China Sea, etc., the reason of frequent occurrences of high water level in the lower reaches of the Yangtze River is approached.