The research progress of food heater containing aluminum powder doesn’t match the demand of high-quality use of food heater, and the in-depth study of exothermic regularity of food heater containing aluminum powder needs to be carried out. In this paper, the exothermic regularity of food heater containing aluminum powder is investigated by infrared thermal imaging analysis, oxygen bomb calorimeter measurement, scanning electron microscope (SEM) observation and other methods. The results show that a large amount of heat generating agent remained unreacted in the food heater after 15 min of use, and the internal cross-section shows a layered arrangement, which can be divided into three layers from outside to inside. The product conversion rates of different layer are 64%, 100% and 91.3%, respectively, and the structure and chemical properties of each layer are obviously different. The possible reasons for the incomplete reaction are as follows:the structure of reaction products hindered the diffusion of water; the hydrogen gas produced hindered the migration of external water; and the uneven distribution of hydroxide concentration. This study provides basis and guidance significance for the improvement of the formulation and the exothermic quality of food heater containing aluminum powder.