In this research, we demonstrate rapid mechanochemical synthesis of nanocrystalline α-alumina (α-Al2O3) from a starting mixture of hematite (Fe2O3) and aluminum (Al). The formation of α-Al2O3 nanocrystallites occurs during the solid-state reaction and through the reduction treatment. Also in this paper, effects of milling time on the particle size and lattice strain of nanocrystalline α-Al2O3 are investigated. The results indicate that complete reduction is reached only after 2 h of milling in a planetary mill and the crystallite size of obtained α-Al2O3 is in general about 12 nm. Also, it is found that increasing the milling time can effectively decrease the nanocrystalline size and increase the lattice strain of α-Al2O3. Finally, the experimental results show appropriate homogeneity and dispersion of related nanocrystallites.