Abstract: A mesoscale analysis using composite method for three cases of warm section heavy precipition occurring in the Southern China region is presented in this paper. It was noted that a mesoscale convergent line was closely associated with heavy rain and induced the circulation on it's upper air. The distributions of 3-D meteorological element field in the warm-section heavy rain was examined. A series of wave was shown with wave-length about 300km and the heavy rain area just corresponded to the strongest one. Finally a typical structure of flow field about warm-section heavy rain was suggested.