Aluminum powder is a widely-used material in industry, due to owing unique properties. In fact, oxidation enthalpy and high combustion heat are the specifications of the oxidation process of aluminum powders. In this research, the effect of particle size on oxidation kinetics of aluminum powder, its corresponding model, and stress distribution in the oxide crust under non-isothermal conditions were comprehensively investigated. For this purpose, the aluminum powders in different particle size (1-3, 12.5, 38-45, 63-75 and 150 micrometer) went under TG-DSC heat analysis tests (under air atmosphere) at different heating rates (10,30 and 50 ?C/min) up to 1300°C. The results obtained from these tests show that the oxidation of aluminum powder particles in different sizes, occurred in several stages. In fact, reducing particle size can lead to an increase oxidation rate and the effect of heating rate would be reversed so that at the minimum heating rate, the highest oxidation occurs. Our findings were shown that the major part of the oxidation takes place at non-isothermal conditions up to 1000 °C. However the stress distribution in the oxide crust at temperatures above 660 °C is was considered. In this temperature range, the expansion of the melt inside the film and also the shrinkage resulting from the transformation of the oxide structure from ? to ? can impose a high rate of stress on this crust. Although, the rate of the stress resulting from expansion of the melt inside the oxide film was higher than the stress resulting its shrinkage from a quantitative perspective. This shrinkage, as an important factor in the direction of activating the defects presents in the structure of the oxide film, plays a determining role in the occurrence of its rupture.The results were indicated that by reducing the particle size, rupture of the oxide film occurrs at a lower temperature, because of the stress concentration resulting from the microstructure defects. In addition, due to the low volume of melt remaining in the oxide film, the stress relaxation of the particles is reduced. By an increase in heating rate, the crust rupture takes place at higher temperatures. Also, non-isothermal kinetic analysis using isoconversional methods and Coats-Redfern method were illustrated that by changing the particle size, the empirical kinetic triplets [E a , A, and g(?)] have been changed and on the basis of any size,a comprehensive model was introduced. Phase and structural were studied by X-ray diffraction technique (XRD) and scanning electron microscopy (SEM). Particle size imposes an effect on the morphology of the oxide film so that in coarse particles, the oxide blades due to higher volume of molten becomes larger and widerin shape, but in smaller particles, needle blades were increased. X-ray diffraction patterns (XRD) support the presence of residual aluminum with oxide. In general, one can conclude that by changing the particle size and heating rates, reaction kinetics, its model, stress distribution and even the morphology of the oxide crust has been changed. Keywords Aluminum powder, Oxidation mechanisms, Non-isothermal, Tension analysis, Kinetic analysis.