The influence of Ti-Si-Mg-AI wire on microstructure and mechanical properties of SiCp/A1 metal matrix composite joints produced by plasma arc in-situ weld-alloying was investigated. Argon-nitrogen mixture was used as plasma gas and Ti-Si-Mg-A1 flux-cored wires as filled composites. Weldments were submitted to tensile test. Meanwhile, the macro morphology and microstructure of the joints were examined. The result shows that the formation ofneedie-like harmful phase A14C3 is effectively inhibited and the wettability of molten pool is improved by adding Ti-Si-Mg-A1 flux-cored wires. With 15Ti-5Si-5Mg-A1 flux-cored wire as filled composite, the maximum tensile strength of the welded joint is 267 MPa, which is up to 83% that of the matrix composites under annealed condition.