Abstract: With mechanism method, natural potential productivity (light, temperature, water and soil) of wheat and maize in the grain core area of Henan Province was studied. The results showed that there is larger potential to increase the yield of wheat and maize. Furthermore, the potential to increase the yield of maize was much higher than that of wheat, for each potential index for maize productivity was higher than that of wheat, including temperature, weather, and soil. The counties with medium maize yield have larger potential of photosynthesis and temperature than counties with higher and lower maize yield, and the later regions have larger potential of weather and soil than the former. Though the preponderant region of each potential index for wheat and maize was completely different, the general trend was that the largest potential and realistic yield were both in the north and middle region of Henan Province, followed by the east and south-east region, and the lowest potential was in the west and south-west region. The key of building the grain core area of Henan Province is to develop the weather and soil potential of wheat and maize productivity.