Abstract: In this paper, the characteristics of geographical distributions for rice yield components in the Yangtze Valley were described, and also the sinksource relations of different rice varietal types in the concerned region were analysed, based on the following established models or submodels, named, 1) effective panicle number per unit field area, 2) grain number pet" panicle, 3) filled-grain percentage, 4) "rice clock" model for development, 5) "source" yield model, 6) "sink" yield model. The results are of great importance to assessing the climatic suitability of different rice varietal types in the studied region, to finding the climatic constrains on rice yield, to pointing out the way to increase yield and to making decisions in rice managements. The authors finally tested and evaluated the results, using the data taken from the Rice Climatic-Ecological Experiment conducted in the Yangtze Valley between 1985—1986,

Key words: Rice Yield, Rice Yield, Yield Component, Ratio of Sink Yield to Source Yield