Abstract: BNi-2 nickel base brazing filler metal was used in vacuum brazing of hot runner manifold block, and heating process curve should be set according to brazing parts. The setting of heating process curve is one of the most important links in brazing process, which determines quality and efficiency of brazing. In this paper, combined with characteristics of vacuum heating and brazing requirements, numerical simulation method of Ansys finite element software was used to simulate and analyze vacuum brazing of multi-layer hot runner manifold block with thick wall and large volume. By comparing simulation results of different process schemes and different brazing parts, heating law of vacuum brazing process was explored. Thus, the relevant parameters of each stage were adjusted and a reasonable heating process curve was formulated, which avoided the waste of resources caused by repeated debugging parameters on site, saved time and cost, and improved efficiency. In addition, thermocouple was arranged to measure temperature of brazed parts during the actual brazing experiment, and the comparison with numerical simulation results showed that the two were basically consistent, which verified accuracy of finite element analysis, and could provide a reference for vacuum brazing of other parts in the future.