Abstract: Moisture migration reflects energy exchange caused by any kind of imbalance potential such as temperature, pressure and humidity. In order to reveal the moisture migration rules of corn ear, the absolute water potential, moisture diffusion coefficient and activation energy of corn ear were analyzed during the natural ventilation based on the absolute water potential theory and the absolute water potential was used to represent the imbalance. Corn ear nature ventilation experiment was carried out in 4 self-made rectangular test granaries. Experiment granaries were placed outside from north to south. Weighing sensors placed at granary bottom could record granary's overall quality in real time and calculate the moisture content of corn ear indirectly in every granary. There were 84 temperature sensors distributed in 4 granaries. The experiment monitoring system began to monitor from December to next April, and the storage period was about 4 months. Results indicated that drying corn to safe moisture at low temperature needed 3 or 4 months in the natural ventilation process, the absolute water potential of air and corn ear increased with the increase of temperature, and the corn ear was in the desorption state when the corn absolute water potential was greater than the air absolute water potential. When the absolute water potential of corn and air approached gradually, the corn moisture remained unchanged because water molecules lacked sufficient thermal energy to overcome the resistance which prevented water molecules evaporating from the grain surface to ambient air. Moisture migration from west to east was affected by water potential gradient in 4 granaries, corn moisture declined faster in windward side than others, and lower drying rate could be received during the initial period of natural ventilation. Corn moisture diffusion coefficient was in the range of from 2.563?10-12 to 5.340?10-12 m2/s, the change of moisture diffusion overall tended to increase with the increase of temperature but it exhibited a downward trend in the late stage affected by the absolute water potential. Different averages in different width of granaries indicated moisture diffusion coefficient was affected by grain thickness. In the process of moisture migration, moisture diffusion coefficient showed the moisture migration changes over time inside the material, and activation energy showed the energy level of water molecules in the diffusion and evaporation. Both of them were the important parameters for moisture migration dynamics analysis. Activation energy could express the need of energy that per mole water was broke away from the material in the drying process. Analyzing the activation energy could estimate the lowest energy consumption and how easily the material was dried. Arrhenius equation could describe the relationship between moisture diffusion coefficient and temperature, by which the obtained average activation energy was 35.76 kJ/mol. Water migration was a complicated heat and mass migration process, and grain was impelled continuously to desorb and absorb due to the gradient of temperature and humidity. Dynamics analysis on water migration can judge the equilibrium state of grain and ambient air, and predict the water migration direction, the moisture variation rate and the concentrated area of damp and hot during the drying and storage process. It can provide the theoretical basis for grain moisture control and early warning.