Abstract: The casting defects of SiC particle reinforced aluminum matrix composites were repaired by friction stir molding. The microstructure, mechanical properties and friction and wear properties were compared and analyzed. The results show that the friction stir molding process can repair the defective microstructure and refine the grains. The shear force during stirring can break the SiC particles and make them evenly distributed in the matrix material, improving the mechanical properties of the material. The tensile strength and yield strength of the material were increased by 14% and 16%, respectively. After friction stir molding repair, the stability of friction coefficient was improved remarkably.