Abstract: Vacuum diffusion brazing of 1 Cr18 Ni9 Ti stainless steel was carried out by BNi82 Cr Si B brazing filler metal with a thickness of 50μm. Microstructure of joints was observed and analyzed. Tensile strength of joints at room temperature was tested and hydraulic strength of joints was examined. Test results showed that brazing filler metal formed a brazing seam with base metal,and the brazing seam had uniform microstructure after diffusion brazing. Tensile strength of joints was equal to that of base metal,while elongation and section shrinkage rate of joints were lower than those of parent metal,and fracture form was ductile fracture. Hydraulic test with 27 MPa and 10 min holding time was carried out on groove simulation parts,and no deformation or leakage was founded,which met design requirements.