The effect of Ti-Al on microstructures and mechanical properties of SiCp/Al MMC joints produced by plasma arc in-situ weld-alloying was investigated, in which argon-nitrogen mixture was used as plasma gases and Ti-Al alloy as filling composite. The results show that the formation of needle-like harmful phase Al4C3 is effectively prevented in the weld by in-situ weld-alloying/plasma arc welding with Ti-Al alloy sheet filler whose titanium content is more than 20%. The fluidity of molten pool is improved, and stable molten pool is gained for the addition of the Ti-Al alloy. The mechanical properties of welded joint are effectively enhanced by the compact-grain structure and the new reinforced composites such as Al3Ti, TiN, AlN and TiC welded joint. The test results of mechanical property show that the maximum tensile strength of welded joint gained by adding Ti-60Al alloy is up to 235 MPa. The factors influencing the tensile strength were also investigated.