Abstract: On the basis of vacuum brazing test of isostatic pressed graphite/BNi-2/304 stainless steel, residual stress and distribution of brazed joints under different brazing gaps were simulated by finite element analysis software, and simulation results were analyzed and explained in combination with the test to identify weak area of brazed joints. The results showed that residual stress in 304 stainless steel side and BNi-2 brazing filler metal layer had little effect on strength of brazed joints for isostatic pressed graphite pipe and stainless steel pipe brazed joints. With the increase of brazing gap, radial residual stress decreased and strength of brazed joints increased. However, when brazing gap was too large, brazed joints were broke by tensile force and affected connection of base metal. The simulation analysis showed that connection of base metal was not sufficient when brazing gap was about 50 μm. When brazing gap was about 150 μm, good brazed joints were obtained. When brazing gap was about 250 μm, brazed joints produced annular cracks under combined action of radial residual stress on the 304 side and the graphite side. When brazing gap was about 350 μm, weak area of brazed joints was isostatic pressed graphite about 900 μm away from the top of brazed joints along the axis and 600～1 000 μm away from brazing filler metal along the radial direction, and annular cracks were derived to the end face of brazed joints.