Using filler metal BNI94 SIB980-1065, the 2 nd stage diffuser of Z8 CND17-04 is vacuum brazed by adjusting the tooling weight under the brazing specification of 1 130 ℃/10 min. Meanwhile, the change of blade height before and after vacuum brazing, brazing weld quality and brazing penetrate ratio are analyzed by th e metallographic microscope and ultrasonic analysis instrument. The results show that when the tooling weight is 56 kg, the quality of the brazing weld is poor and the warping of the part reaches 0.75 mm; as the tooling weight increases, the quality of the brazing weld and the warping of the part improve. When the tooling weight is 94 kg and the blade height is controlled within the specific range, the brazing joint quality is good, the warping of parts is controlled within 0.5 mm, and the brazing penetration ratio is over 90%.