Abstract: In order to study the influence of Fe element on the microstructure of brazing joints of stainless steel using nickelbased filler metal,vacuum brazing of pure Fe was performed using BNi-2+40% BNi-5 composite filler in the paper.The microstructure,the element distribution,the phase composition and the element diffusion of the brazed joint were investigated by using metallographic analyzer,scanning electron microscopy(SEM),energy dispersive spectrometry(EDS) and computing Thermo-Calc and Dictra software.The results indicated that the joint of pure Fe were composed of γ-Ni solid solution and Cr-B intermetallic compound.The results which were calculated by Thermo-Calc and Dictra software showed that metallurgical solidification had not been finished when the temperature was cooled down to 1 173 K and eutectic reaction happened during this phase.This moment the computed results of the phase composition and the element diffusion behaviors are basically consistent with expermental results,which can be used for making the new technology of brazing.