The effects of addition element Co on the properties of Ti-Zr-Ni-Cu brazing filler metal are studied. Microstructure and mechanical property of Ti3Al brazed joints with Ti-Zr-Ni-Cu brazing filler metal are also influenced by the addition element Co. The results show that the wettability and fluidity of Ti-Zr-Ni -Cu-Co brazing filler metal are well improved．Addition element Co can significantly enhance the tensile strength of brazed joints.