<p>Aiming at the problem that silicon carbide particle reinforced aluminum matrix composites (SiC_p/Al MMCs) are prone to interfacial reaction between the matrix Al alloy and reinforced SiC particles at high temperature, which forms Al₄C₃ brittle compounds that affects the joint performance, an oscillating laser wire-filling welding process with preseted gap was developed. The high-quality welding connection of SiC_p/2009Al MMCs with a thickness of 1.6&#xa0;mm and 30% vol was achieved by optimizing the process parameters, and the microstructure and mechanical properties of the joint were analyzed. The results show that the preseted gap can effectively reduce the dilution rate of the base metal, reduce the number of holes, and reduce the generation of the brittle Al₄C₃ phase. With a 1.3-mm gap, a welded joint with good surface forming and no defects such as pores, undercuts, and inclusions could be obtained. The dilution rate of the base metal was about 12%, and the size of the Al₄C₃ brittle phase was reduced from tens of microns to submicron levels with its number significantly reduced. The microstructure of the weld zone (WM) was dominated by dendrites, while the vicinity of the fusion zone (FZ) presented a mixture of equiaxed, dendrite, and columnar crystal phases. The tensile strength of the welded joint was 233 ± 3&#xa0;MPa. The elongation after fracture was about 3% with all fracture positions near the fusion line, showing the characteristics of brittle-ductile fracture. The lack of Cu element and the insufficient strengthening phase of <i>θ</i>′ (Al₂Cu) result in low microhardness in the WM region.</p>