The in-situ TiB2/2219 aluminum matrix composite ingots were prepared by using the high-temperature-mixed molten salt method. The effect of TiB2 content on microstructure and properties of in-situ TiB2/2219 aluminum matrix composites is investigated by optical microscopy, scanning electron microscopy, X-Ray diffraction, combined with elastic modulus, room temperature tensile and Charpy impact test methods. The results showed that the TiB2 mass fraction increased from 0 to 5%, and the TiB2 particle size and the average grain size of TiB2/2219 aluminum composite ingots decreased. The elastic modulus, tensile strength, and yield strength of TiB2/2219 aluminum matrix composite increased significantly as TiB2 content increased, but the ductility and impact toughness decreased. The elastic modulus, tensile strength, yield strength, and ductility of 5% TiB2/2219 aluminum matrix composites plate were 88.7 GPa, (474.2±2) MPa, (400.6±1) MPa and (4.7±0.1) %, respectively.