nanocomposite has been prepared by mechanical alloying of Fe 3 O 4 , Al and Si powder mixture and heat treatment. Powder XRD patterns, TEM and HRTEM images and XPS spectra revealed the crystalline transformations from raw materials to Fe 3 Si-Al 2 O 3 nanocomposite during mechanical alloying and annealing and from Fe to Fe 3 Si to a mixture of Fe 3 Si, Fe 5 Si 3 and FeSi with the proportion of Si in raw materials increasing. The average particle size of smaller Fe 3 Si nanoparticles was about 20 nm and the aggregation under high temperature leaded to larger Fe 3 Si nanoparticles with average particle size of about 60 nm. 57 Fe M€ ossbauer spectra illustrated the existence of amorphous phases and effectively supplemented other characterisation results. The samples exhibited ferromagnetic behaviour with hysteresis loops and their saturation magnetisations decreased with the proportion of Si in samples increasing.