Sapphire/metal welding connection faces the challenge of poor wetting of sapphire surface by brazing materials. The interface structure of the sapphire/Ag-Cu-3Ti/TC4 alloy brazed joint, the effects of temperature and holding time on the shear properties, and the mechanism of interface connection were studied. The results show that the sapphire side forms a dense metallurgical reaction layer. The microstructure of the reaction layer is composed of Ag base solid solutions, Cu base solid solids and the crystal. TC4 alloy side forms a crispy layer and a crystal infiltration area. With the increase in brazing temperature, the shear strength of the brazed joint reduces significantly. As the holding time is prolonged, the shear strength of the brazed joint increases firstly and then decreases. The fracture surface of the brazed joint exhibits a mixed fracture morphology of the sapphire brittle fracture and filler metal “adhesive type” fracture. The brazing connection relies solely on the metallurgical bonding strength between a small portion of Ag-Cu-3Ti brazing metal and the sapphire. During the brazing process, Ti and Cu diffuse towards the sapphire side and accumulate on the surface of Al₂O₃. Sufficient solid-liquid interaction occurs at the interface to form stable intermetallic compounds, and the TC4 alloy side grains continuously grow towards the matrix, resulting in a significant increase in the shear strength of the brazed joint.