Abstract: TC4 titanium alloy and sapphire were brazed with 0.3wt% GNSs-AgCuTi composite solder. The interfacial microstructure and Gibbs free energy of different interface products were studied. The effects of brazing temperature on the microstructure and mechanical properties of brazing joints were studied. The results show that Ti₃Cu₃O and TiC are easier to form than Ti-Cu intermetallic compounds. With the increase of brazing temperature, the atomic diffusion capability between the base metal and the weld is enhanced, which results in the increase of the thickness of the diffusion layer and reaction layer at the side of titanium alloy and sapphire. When the brazing temperature is too high, the Ti-Cu intermetallic compound can be fully grown, resulting in a decrease in joint strength. When the brazing temperature is 850 ℃ and the holding time is 10 min,the shear strength of the brazed joint is the highest, which is 28.5 MPa.