Aluminum matrix composites reinforced with micro-TiB₂ and nano-Al₂O₃ particles were successfully fabricated by combining powder metallurgy and hot rolling with raw materials of fine atomized aluminum powders and TiB₂ particles. The Al₂O₃/TiB₂/Al composites exhibited a yield strength of 258.7 MPa and an ultimate tensile strength of 279.3 MPa at 25 °C due to the comprehensive strengthening effect of TiB₂ and Al₂O₃ particles. The strengthening effect of TiB₂ particles was significantly weakened with temperature rising to 350 ℃, and the Orowan strengthening mechanism between nano-Al₂O₃ and dislocation made the yield strength and tensile strength of the composite material reach 98.2MPa and 122.5MPa. After annealing at 350 ℃ for 1000h, due to the pinning effect of nano-Al₂O₃ on grain boundaries, the grains growth were suppressed significantly and the strength and hardness did not decrease significantly. The main fracture mechanism of composites changed from brittle TiB₂ particle fracture to interface debonding between TiB₂ and the matrix from room temperature to elevated temperature.