Abstract: Aluminum matrix composites for building reinforced TiAl₃ particles were prepared by ultrasonic vibration and in situ reaction. By optical microscopy and scanning electron microscopy analysis, the effects of microstructure evolution and TiAl₃ of different mass fractions on the hardness and mechanical properties of aluminum alloys were investigated. The results show that TiAl₃ new phase is formed by ultrasonic vibration after adding K₂Ti F₆ to ZL101 aluminum alloy, TiAl₃ particles play a fine grain strengthening role. When the TiAl₃ content reaches 1.0%, the primary α-Al phase of aluminum matrix composites is fine and round, the TiAl₃ particles are small, the distribution is uniform, and there is no obvious agglomeration phenomenon.The tensile strength of 1.0% TiAl₃ /ZL101 composite is 285.2 MPa, hardness is 102 HB and elongation is 2.82%, which is 24.7%, 52.2% and 15.1% higher than that of ZL101 aluminum alloy, respectively.