In this article the potentiality of agricultural climatic resources is approximately estimated. 1℃ temperature change and 100 mm rainfall change are taken as units of climatic variation. In the case of 1℃ temperature change, the potentiality of agricultural climatic resources might have a change about 30 million tons of grain in magnitude; in the case of 100 mm rainfall change, the change of potentiality would be 80 million tons. Besides, analysing the greatest amplitudes of climatic change in historical and geological times, the author succeeds in giving some preliminary deductions of possible impacts of climatic variation in different time scales, which may be summarized as a climatoecological series.