Based on the TBB grid data from the FY 2E satellite and NCEP\\NCAR reanalysis data and the data of the heavy rainfall from 31 May to 2 June 2010, the features of mean TBB field distribution and evolution are analyzed to reveal the internal relationship between strong rainfall cloud dissipation and heavy rainfall development. The results show that the development of these Mesoscale Convective Complexes (MCCs) was associated with the formation and evolution of several cloud clusters in South China．There were obvious corresponding relationships between low TBB area and precipitation location. The rapid TBB decrease and rainfall enhancement were quite coherent. The evolution of strong rainfall and the changes of TBB gradient had apparent correspondent relationship; the sudden decrease was followed by the strengthening of rainfall, and vice verse. When TBB decreased to the lowest, rainfall reached the strongest. The transported water vapor from the South China Sea along the west side of the subtropical high and the constant flow from Upper trough met in South China, which played an important part in the generation, development, and maintenance of the strong convective cloud cluster in Guangxi. The lower TBB band along the central Guangxi and warm shear was less dynamically stable with a small north to south swing, which resulted in the torrential rainfall.