Abstract: The effects of the filler alloys with different compositions on microstructure and properties of SiCp/6061Al matrix composite joints welded by plasma arc welding with argon-nitrogen mixture as plasma gas and Al-Ti-Ni-Si alloy as filler were investigated.The results show that the microstructure of the weld joints filled with Al-Ti-Ni-Si alloy was homogeneous and compact,and a little needle-like phases with length of 50 μm was found.The amount of Al3Ti phase in the fusion zone was less than that in the center,and no gray needle-like Al4C3 phase was found.The joint with Al-5Ti-5Ni-5Si alloy as filler had more reinforced phases than that with Al-10Ti-10Ni-3Si alloy,and the reinforced phases assumed disordered state,no needle-like phase was found.The weld joints were composed of AlN,Al3Ti,TiC,Ni3Al,NiTi2 and Ti5Si3.The tensile strength of the two joints was 215.0 and 2215 MPa respectively.