Abstract: AgCuInTi active filler foils were used for brazing Mo and Kovar alloys at 750 ℃ and 800 ℃, respectively. The microstructure and mechanical properties of the joints were characterized and analyzed by scanning electron microscopy and shear test. The active connection reaction mechanism of Ag CuInTi alloy brazing filler metal was further analyzed. The results show that the amount of Ni atoms dissolved and diffused into the brazing seam is much higher than that of Fe and Co atoms during the brazing process, and Ni₃Ti intermetallic compounds formed with Ti atoms are distributed in the brazing joint. With the increase of brazing temperature, more Ni atoms in Kovar alloy dissolve, which leads to the rise of the Ni₃Ti brittle phase in the joint and the decrease of the shear strength of the joint. The shear strength of the joint brazed at 750 ℃ for 10 min reaches about 189 MPa.