Abstract: The regional test yield of certain certificated grain varieties is a reachable yield in current natural and technical condition. The cropping system was determined for every agro-ecological region, through which the potential climatic productivity could be sufficiently developed. Based on the regional test yield of the certificated grain varieties and the cropping system, the grain potential productivity of per area was calculated. The total grain productivity of every county, province and the Main Land of China was obtained by multiplying the potential grain productivity of per area and the cultivated land area in 2004. By comparing it with the real yield, the capacity of increasing production and its difference between every province was acquired. The results show that the total grain potential productivity of the Main Land of China is 0.92 billion ton in 2004, and that there is large gap between the potential grain productivity and the real yield, averaging 0.45 billion ton in recent three years, and high assurance for grain security at present. From the results of every province, the average potential grain productivity of per unit area takes on a descendent decline from the provinces in the southeast to those in the northwest of China, apart from Sinkiang, while that of Inner Mongolia, Ningxia, Gansu, Qinghai, Tibet, stretching from northeast to southwest of China, is lower than that of the others. The capacity of increasing production per area captured the same trend as the average grain potential productivity per area, which indicates that the more potential grain productivity, the more capacity of increasing production for a province. The provinces lies in the north and southwest of China witnesses much room for increasing production because of their large exploitation coefficient. As such, in order to ensure the food security, the food production in the east and middle of China, where basic agricultural bases are relative better, should be more emphasized. In addition, basic agricultural infrastructure construction, land consolidation and the improvement of medium or low-yield cultivated lands should also be advocated in the north and southwest of China to explore the grain potential productivity.

Key words: Grain potential productivity, Grain yield, Cultivated lands, China