Abstract: The flood event in the middle Yangtze River(Changjiang River)in 1998 is simulated and rebuilt,utilizing a numerical model characterizing flood routing in the river-lake system,to quantificationally analyze how the changes of three diversion rivers along Jingjinang reach,of Dongting Lake storage volume,of flood storage & diversion have influenced the flood situations in Jingjiang reach,Dongting Lake,and Chenglingji-Hankou reach.Combined with qualitative physical interpretation,the cause of abnormally high flood stages in 1998 and its interaction with flooding in the river-lake-coupled system are thoroughly discussed.In addition,the effects of restoring the farmland to natural state and of Three-Gorge Reservoir in the flood in 1998 are presented.