Abstract: The mesoscale convective system producing heavy rainfall is an important system during the rainy season. The research on its organizational structure, activity patterns and the development of mechanisms is of great significance to improve the storm forecasting ability. In the past three years, based on the project from the National Natural Science Foundation of China, we have been carrying out a series of studies on MCSs, including organizational model, structure characteristics, environmental conditions, and topographic effects on precipitation, especially the mountain-plain stream and meso-scale terrain. The couping force of wet baroclinic thermal power leads to the development of MCSs. Finally, the physical conceptual model of mesoscale convective systems producing heavy rainfall in the Yangtze River valley is summarized.