Abstract: High-temperature filler metal of TiNiB prepared by arc melting was used as an active filler metal in vacuum brazing of TiAl alloy.The effect of brazing temperature on the microstructure evolution of the joints was studied in this paper.The TiNiB filler metal was mainly comprised of TiNi and TiNi₃ eutectic microstructure,in which some TiB₂ blocks appeared.The melting point of the filler metal was 1 120℃.The dissolution of TiAl substrate has a strong effect on interfacial structure.The TiAl alloy adjacent to brazed seam was transformed to β layer with the dissolution of TiAl substrate.The microstructure of the brazed seam was comprised of Ti-Al-Ni compounds and a little β phase.TiB₂ was transformed to TiB due to the reaction with Ti.