Owing to the complementary mechanical properties and good physicochemical compatibility of Ti₃SiC₂ and Al₂O₃, Ti₃SiC₂/Al₂O₃ composites are considered as ideal structural materials. However, the low purity of Ti₃SiC₂ phase is the bottleneck problem in the preparation of Ti₃SiC₂/Al₂O₃ composites through an in-situ reaction. In this study, Ti₃SiC₂/Al₂O₃ composites with different Al contents were prepared at different temperatures via hot pressing sintering. Al, as a sintering aid, improved the purity of the Ti₃SiC₂/Al₂O₃ composites. This is because Al could partially replace Si in Ti₃SiC₂ lattices, which stabilized the lattice of Ti₃SiC₂. Furthermore, the introduction of an appropriate amount of Al could promote the densification sintering of Ti₃SiC₂/Al₂O₃ composites and improve the mechanical properties. The sample prepared at 1450 °C with 0.2 mol Al addition showed the best comprehensive properties, whose relative density, Vickers hardness, flexural strength, and fracture toughness were 99.48%, 16.72 GPa, 608.21 MPa, and 8.73 MPa.m^1/2, respectively.