Abstract: In order to grasp the frequency characteristic of heavy rainfalls in the Changjiang and Huaihe River Basin during the plum rain season in 2011, reveal the occurrence and development mechanism of rainstorm weather, to provide a useful reference for future forecast of rainstorm. The three heavy rainfall processes which occurred in June 25th, July 5th and July 12th were analyzed by using the conventional observational data, mesoscale dense observational data, radar data and products of numerical model. The result showed that: the heavy rainfalls which occurred in June 25th and July 12th caused by the interaction of the cold air of Westterlies and low level trough, the south airflow on the eastern side of the inverted trough transmitted adequate water vapor, the front belonged to stable rainfall, which caused by the interaction of the weak cold air and the external cloud of strong tropical storm ‘Meari’, the later belonged to convective rainfall. The heavy rainfall in July 5th which occurred at the edge of the west pacific subtropical high caused by unstable stratification of the cold air in the high and warm in the low and adequent water vapor supply transmitted by low level west-south jet. Base reflectivity map of Doppler radar could trace echo of heavy rainfall well, which could play an important role in heavy rainfall weather defense and nowcasting warming.