Abstract: Vacuum brazing of pure Fe, Ni, Mo, Cr metals was performed using 60%BNi-2+40%BNi-5 nickle-based composite fillers. The microstructure, the composition distribution, phase composition and microhardness of the brazed joints were investigated using optical microscopy, scanning electron microscopy, energy spectrometer, X-ray diffractometer and microhardness tester. The results indicate that Si and B in the brazing seam diffused insufficiently when the base metals were pure Fe and Cr, forming brittle compounds in the seam, the hardness of joint was higher. The brazing seam of pure Ni, Mo metals were completely composed of solid solution, its hardness was lower and at the same time the voids generated at the interface of the joint when pure Ni metal was brazed, the hardness of joint was lowest.