Abstract: Using the daily precipitation data from 52 meteorological stations in the mid-lower reaches of the Yangtze and NCEP/NCAR reanalysis data from 1961 to 2009, the characteristics of spring and Meiyu precipitation are analyzed. It shows that spring precipitation takes on significant inter-annual and inter-decadal variations while Meiyu precipitation doesn't. Based on the annual spring and Meiyu precipitation characteristics, it is divided into four classes: Flood-flood, flood-drought, drought-drought and drought-flood. Generally, drought-drought and flood-flood events take place frequently. The variation of circulation features affects the precipitation anomaly too. The mechanism of different type is also discussed, finding the correlation coefficient between previous winter Niño3 index and spring, Meiyu precipitation to be 0.42 and 0.30, which reach 0.01 and 0.05 levels, respectively. The previous winter snow of Tibetan Plateau and western Pacific summer monsoon index are shown both significantly correlated with Meiyu precipitation. The abundant water vapor is carried by the anomalous southerly from the South China Sea and the western Pacific, the western Pacific subtropical anticyclone strengthens, and its position leans westward in June. That would make a successive flood event. When water vapor over the reaches is abundant but insufficient in source region, position of the western Pacific subtropical anticyclone appears from west to east anomaly in spring and Meiyu periods, and that would cause the flood-drought events. When water vapor is insufficient in both areas, drought event occurs. In 2011, a sudden turn of drought and flood takes place in the mid-lower reaches of the Yangtze, leading to big economic losses of agriculture. The factors which may cause the sudden turn of drought and flood events are analyzed. The sea surface temperature anomaly of the equatorial eastern Pacific happens in precious winter and less water vapor cause spring drought, and with Meiyu occuring, the western Pacific subtropical anticyclone moving westward and precipitation increasing greatly. On the basis of preliminary analysis of related impact factors, numerical experiments are needed to evaluate the result further.