Abstract: The particle size, morphology, structural features and changing rules of microstructure of elemental Al, Fe and Ni powders during mechanical alloying have been studied by SEM, EPMA and X-ray diffraction. The change of solid solubility of Fe and Ni in Al and effects of ball-milling condtions on micro-strain and micro-grain size have been measured. The results show that the solution of Fe and Ni in Al and the decrease of grain size occur simultaneously, but all these must be based on the premise of the fine layer structure of three kinds of powder having been formed at the initial stage of ball milling process.