Abstract: The microstructure and filler metal element diffusion behavior of brazing joint interface were studied after titanium TA1 was vacuum brazed with Ti-37.5Zr-15Cu-10Ni titanium-based amorphous filler metal. The results show that the brazing joints consisted of brazing joint, interface region between brazing joint and base metal, diffusion region of small needle and strip, diffusion region of dense flake and diffusion region of large flake, and the corresponding microstructures were β phase, β phase+small strip α phase, widmanstatten, coarse widmanstatten+(Ti, Zr)₂(Cu, Ni) intermetallic compound and α phase+Ti₂(Cu, Ni)+TiNiFe intermetallic compound, respectively. The diffusion distance to titanium matrix of Ni was the longest, the diffusion distance of Cu was the second, and the diffusion distance of Zr was the shortest. Zr could form continuous solid solution with α-Ti and β-Ti, but the ability of β phase to dissolve Zr atoms was stronger than that of α phase; Cu and Ni were mainly both solubilized in β phase.