To utilize desulfurized gypsum， which is an industrial waste produced by flue gas desulfurization， the melamine resin-reinforced desulfurized gypsum-fiber composite system was studied. By matching and optimizing the curing conditions of the melamine resin with the hydration molding process of gypsum， combined with the analysis of the structure and morphology of the composite system， the gypsum composite board with excellent comprehensive properties was developed. The results show that the reasonable coordination and matching between the curing and crosslinking of the melamine resin and the growth process of gypsum whiskers not only help to form a close combination of organic and inorganic， but also help to strengthen the adhesion between the desulfurized gypsum whiskers and glass fibers， promoting the realization of the strengthening effect of the melamine resin on the material performance. The flexural strength of the gypsum composite board is not less than 18 MPa， the compressive strength is greater than 25 MPa， the elastic modulus is greater than 6 500 MPa， and the 24 h water absorption ratio is less than 3.0%. The main performance exceeds that of traditional cement or calcium silicate type basic board， with obvious technical and market development prospects.