Abstract: Failure reasons of brazing seam of sinter-brazing shift fixed block in a certain platform were analyzed by means of macroscopic observation, metallographic examination, mechanical property test, scanning electron microscopy analysis and energy spectrum analysis. The results showed that due to influence of sintering process and base metal, there was a loss of brazing filler metal to the surface of base metal after sintering during production process, and excessive infiltration of brazing filler metal into base metal after heat treatment, which resulted in insufficient brazing filler metal in brazed joint. At the same time, there was deformation phenomenon after heat treatment. Both of them did not form fillet of brazed joint, metallurgical reaction to brazed joint was insufficient, and effective bearing area of brazed joint was small and the strength was low. It was suggested to control production process of sinter-brazing parts strictly, improve brazing process and increase yield of finished products.