Abstract: This study synthesized an Er-doped TiC/A356 composite through ultrasonic-assisted process to achieve microstructure homogenization and enhanced mechanical strength. Systematic investigation was conducted to evaluate microstructural evolution and corresponding mechanical performance. The analytical results demonstrate that the synergistic interaction between Er and TiC reinforcements effectively refines the average α-Al grain size from 730 μm to 122 μm while transforming eutectic silicon morphology from coarse lath-like to fine granular structures. The composite containing 0.2 wt%Er and 1 wt% TiC exhibits optimal comprehensive mechanical performance. In as-cast condition, it demonstrates a tensile strength of 193 MPa with 7.7% elongation, representing 17.0% and 175% enhancement relative to the A356 matrix alloy,respectively. After T6 heat treatment, the material achievs a yield strength of 267 MPa and ultimate tensile strength of 315 MPa, corresponding to 36.2% and 17.5% improvements compared to the matrix alloy.