TiC nanoparticles reinforced AlMgSc composites are prepared based on selective laser melting (SLM) forming process, and the phase composition, microstructure and mechanical properties of TiC/AlMgSc composites are studied. The results show that TiC/AlMgSc composites with high density (99.73%) are obtained by using the optimized SLM forming process parameters. There is no reaction between TiC particles and AlMgSc matrix during SLM forming. TiC particles provide high-density effective nucleation points, which promote the transformation of the composite structure to equiaxed grains and grain refinement, and weaken the texture strength. After adding TiC particles, the tensile strength of the composites increased by 9.9% to 611 MPa, and the elongation decreased to 10.02%. The fracture mechanism of the composites is mainly ductile and brittle mixed fracture, and TiC clusters with a size of 3?8 μm remain on the fracture surface and adhere to the aluminum matrix.