High-energy mechanical milling (HEMM) and sintering were employed to fabricate an Al alloy matrix composite reinforced with subsive-sized Al 2 O 3 particles. Al–(Mg, Cu, Si)–SiO 2 , composite powders were prepared by HEMM. Nano-sized SiO 2 particles embedded in Al–(Mg, Cu, Si) matrix particles were obtained by HEMM. Al-based metal matrix composite reinforced with subsive-sized Al 2 O 3 particles was fabricated successfully by sintering at 650 and 750°C for 2h using milled powder. Subsive-sized Al 2 O 3 particles and eutectic Si were formed by in situ displacement reaction between Al and SiO 2 during sintering, and homogeneously distributed in the Al–Si–(Mg, Cu) matrix. The flexural strength of the sintered specimen (1.2GPa) using 8h milled powder was about four times as the sintered specimen using as-mixed powder.