The seasonal variations of heat sources and moisture sinks over the middle and down reaches of Yangtze River and their relations with the evolutions of precipiation and wind are discussed using ECMWF data and rainfall from 1980 to 1986. There are most intense heat sources in spring

and stronger ones in summer

and stronger moitsture sinks from March to November except August

with peak values in June and Octomber. The latent heat plays an most important role in the atmospheric diabatic heating process

especially during the spring rainy season and Meiyu season. There are most prominent radiative cooling rates during summer. The precipitation during the period of Meiyu is primarily due to convective activities in the atmosphere

and the evaporation plays an important role in the process of water cycle. The transition seansons for vertical distributions of heat source and moisture sink occur in April and from late September to early Octomber.