Using the high resolution simulations of WRF model and the calculation scheme of grid-based moist available energy,this paper analyzes the space-time evolution characteristics of moist available energy in the occurrence and development processes of a strong rainfall weather during the Jianghuai Meiyu period,and qualitatively and quantitatively discusses the interaction mechanism of the transition term,the advection term and the vertical transport term in the energy equation from the energy budget balance.Results show that,in the strong rainfall process,the space-time characteristics of moist available energy have good corresponding relations with the occurrence and development of heavy rain.The range of 40×10⁴ J·hPa^-1·m^-2 contour of 800 hPa moist available energy in the lower troposphere and the contour extending to near 500 hPa can be used as necessary conditions for the heavy rainfall occurrence.The rapid energy accumulation at 2—3 h before heavy rain and its impact on the moving direction of rainfall areas have a good indicative function to rainstorm forecast.The horizontal and vertical transport and transition of moist available energy ensure the energy accumulation and the energy increase in the middle troposphere,which provide sufficient energy for the occurrence and maintenance of heavy rain.