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Based on the data from meteorological observation stations in Shandong Province from 1961 to 2008, the yearly average climatic potential productivity of grain crops (winter wheat and summer maize) is calculated by the phase correction method, and the spatial and temporal variation characteristics of climatic potential productivity of grain crops are analyzed by the decomposition method of the empirical orthogonal function. The results show that there were obvious inter annual fluctuation and regional difference in climatic potential productivity of grain crops. The productivity in a rich harvest year was 3 to 9 times of that in a poor harvest year for winter wheat and 2 to 3 times of that for summer maize. The area of high productivity of grain crops was in the south part of Shandong Province with better hydro thermal conditions and low productivity was in the east coastal area of the Shandong Peninsula. The annual variation of the yields was consistent with that of climatic potential productivity. The yields of grain crops, especially for summer maize, were affected remarkably by climatic condition in growth season in Shandong Province. There was good spatial consistence in climatic potential productivity of grain crops in the whole province. The grain crop productivity fluctuated due to unstable monsoon climate. Regional complementarity of grain production was relatively poor in Shandong Province.