Abstract: Plasma arc "in-situ" welding of SiC_p/Al MMCs were carried out using argon-nitrogen mixture as plasma gases with Ti-Ni alloying as "in-situ" material.The results showed that the new composite reinforced phases are produced in the seam, such as TiN, TiC, AlN, Al₃T, Al₃Ni, which ensured the quality of joints, but the needle-like brittle phases Al₄C₃ is not found, the metal Ni reduced the solubility of SiC, and increased the crystallization heat greatly, which improved the fluidity of weld pool.The new reinforced phases like AlNi, Al₃Ni improve the mechanical properties of weld seam effectilvely.The mechanical testing results showed that the maximum tensile strengths obtained with Ti-Ni alloy as "in-situ" material are 215.4 MPa, which is about 67.3% of the base metal stength.