Abstract: The present invention relates to a method for manufacturing a core plug of a gas turbine vane, and more particularly to plan and design a core plug formation using brazing comprising: a first step of designing and planning a formation of a core plug; a second step of cutting a Hastelloy X plate according to the design of the core plug; a third step of fabricating a preform of the core plug; a fourth step of spot-welding a trailing edge; a fifth step of pasting a brazing filler; a sixth step of performing brazing heat treatment; a seventh step of performing grinding a brazed portion; an eighth step of performing a grit blasting. According to the method for manufacturing a core plug of a gas turbine vane using brazing of the present invention above-mentioned, there is a significant effect of reducing manufacturing cost by in which the process is simple, and there is no deformation, shrinkages, cracks, and the like, in contrast with a conventional welding method.