Abstract: Based on precipitation data, hydrological information and the NCEP/NCAR reanalysis data during 1981-2012, the floods precipitation and weather features are analyzed for the Yangtze River and Dongting Lake area. The similarities and differences of weather characteristics are compared between the floods events regions. in the upper Yangtze River and Dongting Lake regions, during the different dispatch key period for the Three Gorges Reservoir. The results show:The big flood in mainstream of the Yangtze River is impossible for the drawdown period, the big flood may appear in the upper reaches of the Yangtze River for the rainy season and the impoundment periods, and the synchronized floods in the Yangtze River and Dongting Lake occur often between July and September. The east-west direction movement of the subtropical anticyclone in the Western Pacific plays a key role for the Yangtze River flood, the chief factor of flood encountering in the Yangtze River and Dongting Lake regions is whether there sustainable exists an anticyclone circulation in the middle and lower layers of troposphere over the Dongting Lake.