The work aims to analyze the degradation of oxide scale on 5052 aluminum alloy in the hot air and combustion atmosphere of 300 ℃, 400 ℃ and 500 ℃, so as to study the method of determining whether there is accelerant in the fire scene based on the analysis of metal oxide scale after the fire. The combustion atmosphere in the fire scene was simulated by a high temperature oxidation experimental device. Optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and precision electronic balance were used to investigate the degradation of oxide scale on the surface of 5052 aluminum alloy in the air and combustion atmosphere of 300 ℃, 400 ℃ and 500 ℃ and analyze the microstructure. The oxide scale on the surface of 5052 aluminum alloy was closely related to the ambient atmosphere and temperature. Good oxidation resistance appeared in hot air with lower temperature, and the oxide scale generated on the surface was complete and compact. The oxidation rate of 5052 aluminum alloy was significantly increased by high temperature combustion atmosphere. The structure of oxide scale formed on the surface was loose and unstable oxidation occurred with time. The microstructure of oxide scale on aluminum alloy surface in fire records relevant information of fire scene, which is not only an effective supplement to macroscopic morphology evidence of traditional residue, but also can be used as auxiliary evidence for the presence of combustion improver in fire scene.