Abstract: The design and molding scheme of the demoulding tool after fabrication of the reflector are elaborated in this paper, taking fabrication of a kind of resin based carbon fiber composite grid antenna reflector as the research object. The main material used for the grid reflecting surface is Toray T700 and the matrix is 3234 resin system. By studying the design, production and use of composite material molds, the secondary demolding of complex composite products, etc., a new solution to making molds with ductile cast iron and carbon fiber composite materials and adopting vacuum bag autoclave molding technology is put forward. The results show that compared with the traditional metal mold, the composite mold has more stable dimensional accuracy, is simpler to make and lighter under the bigger temperature difference; that the secondary demoulding of grid reflecting surface is realized by using composite material transition die can greatly improve the production efficiency. This method is instructive to fabrication of this kind of grid reflector.