In order to study the interface structure of aluminum core/oxide layer intuitively， the slicing method of aluminum powders （2-8 µm） were successfully established based on FIB micro and nano processing technology. The slices were obtained by combining FIB direct cutting with profile thinning. The interface structure of the prepared slice samples was clear and intact， and the oxide layers were not damaged. The microstructure， crystallinity and element distribution of “Al core/oxide layer” under different ageing conditions were obtained were characterized by SEM， HRTEM and EDS. The stoichiometric ratio of Al and O elements in the oxide layer of aluminum particles deviated from the standard Al₂O₃， showing a gradient distribution. The positive correlation between the oxide layer thickness of aluminum particles and the aging temperature has been quantitatively obtained. The oxide layer thickness of the samples without thermal aging was ~5.4 nm， and the oxide layer thickness of the samples aged at 75 ℃ and 95 ℃ increased to （34.1±2.1） nm and （51.3±2.2） nm， respectively.