Abstract: Vacuum brazing between CZ zircaloy and 316L stainless steel was carried out by using BAg72Cu filler metal, and the interface microstructure and mechanical properties were studied. The results show that the interface of the joint is continuous and compact after vacuum brazing, and good metallurgical bonding is achieved between the filler metal and the base metals.At the brazing temperature of 800, 820 and 850 ℃, the microstructure of the joints from stainless steel side to zircaloy side is Fe(Cr, Zr)₂, Zr(Fe, Cr)₂, (Zr, Cu), Zr₂Ag, α-Zr+Zr₂Cu+Zr₂Ag in turn. When the brazing temperature is 880℃, the Zr₃Fe phase is formed in the joint due to large diffusion of Fe. When it is brazed at 820 ℃, the shear strength of the joint at room temperature is the highest, which is 125 MPa. The joint is hardened obviously after addition of silver-copper solder, and the hardness of the diffusion layer near the stainless steel side is the highest, about 725 HV.Under all brazing processes, shear fracture occurs at the interface between the base metal zirconium alloy and the solder.The shear fracture morphology is typical river patterns and steps, which is brittle cleavage fracture.