Abstract: Hot air drying is one of the most widely used techniques in large-scale processing of grain. However, the existing problem of grain hot air drying is the high cracking rate, which directly reduces the product grade and storage-transportation performance. It is generally believed that the formation of grain cracks is closely related to the wet stress and thermal stress during hot air drying, since the temperature gradient and moisture gradient often lead to uneven shrinkage, which induces the formation of drying stress. According to von Mises yield criterion, when the von Mises stress is larger than its yield limit, the material will fracture or develop cracks. In this paper, corn kernels were selected as the research object due to their high cracking rate dried by hot air. In order to accurately model the changes of drying stress and predict the formation of stress cracks in corn kernels during hot air drying. Firstly, the edge contour and size parameters of corn kernel were extracted by image processing technology and used to reconstruct its three-dimensional geometric model. Then, the information of temperature, moisture and stress in corn kernels was obtained by the stress mathematical model coupled with the heat-mass transfer. Finally, the stress cracking characteristics of corn grain were predicted by comparing their von Mises stress with yield stress. The results showed that: 1) The moisture content and temperature data determined by the hot air drying experiments were good agreement with the results simulated by the heat and mass transfer mathematical model with the maximum deviation 7.28% and 9.64% respectively, which indicated that the drying model can be used to further explore the changes of temperature and moisture in corn kernels during hot air drying. 2) The simulated results showed that the temperature gradient and moisture gradient in the outer layer of corn kernels were larger than those in the inner layer during drying. The same distribution trend was also found for the wet stress, thermal stress and total stress. The average wet stress and total stress increased first and then decreased, while the thermal stress showed the opposite trend. What's more, the thermal stress of corn kernels was obviously smaller, so corn kernels were mainly affected by wet stress during drying. 3) The simulated results of corn drying with different drying conditions (hot air temperature 40-80℃, relative humidity 12%-52%) suggested that the maximum stress of corn kernels decreased gradually during drying, which increased with the increase of hot air temperature and decreased with the increase of relative humidity at the same time. The maximum stress of corn kernels was larger than its yield stress in the early stage of drying, the stress cracking of corn kernels could be inhibited by lower hot air temperature and higher relative humidity. Accordingly, it was significant to adopt the subsection drying technology or increase tempering times in the early stage of drying. The result provide a better understanding for the evolution of drying stress and the formation of stress cracks in corn kernels during hot air drying.