Grain production has an important effect on food security. The pattern of grain productive potentiality in China s major grain production areas will be needed to control food security during climate change. This study aimed to improve two aspects of the mechanism model. First, we revised the coefficients a and b for calculating solar radiation. Second, we divided the study area into different zones according to soil effective coefficients and then constructed evaluation index systems. We used these revised models to calculate the grain productive potentiality at the four levels of photosynthesis, light-temperature, climate and soil. We analyzed climate fluctuation impacts on grain productive potentiality and found that effective growth periods increased in most areas and beginning-days gradually advanced and ending-days were delayed. Sunshine duration time increased and precipitation declined in the crop effective growth period,most of which was focused in the effective growth period. The decrease in precipitation controlled grain production in the study areas and production potential benefited from changes in meteorological factors on the whole. Climate fluctuation had a positive influence on photosynthesis, light-temperature and soil production potential. In contrast, climate fluctuation had a negative influence on climate production potential. The influence of climate fluctuation on photosynthetic, light-temperature, climate and soil of production potential gradually reduced. The increase in photosynthetic production potential of paddy fields caused by climate fluctuation was more than that of dry land and the increase in the light-temperature production potential of dry land was more than that of paddy fields. The decrease in the climate production potential of dry land was lower than that of paddy fields. Climate fluctuation increased the soil production potential of dry land, and decreased the soil production potential of paddy fields.