The invention discloses a method for repairing a traditional building by using glass fiber reinforced plastic materials, and particularly relates to the technical field of ancient building repair. According to the technical scheme, the method comprises a silicone mold, resin, fibers, flexible glue, a water-based environment-friendly paint color, gel coat brushing, fibrofelt, special epoxy resin and sealing vinyl resin. The method comprises the following specific process flows of (S1) analyzing a drawing so as to understand the surface effect and the overall structure; (S2) adopting a mode of separately manufacturing and modeling an arc-shaped tile, a cylindrical tile and a bottom beam and then integrally assembling and combining the arc-shaped tile, the cylindrical tile and the bottom beam; (S3) performing whole modeling on the tiles and the bottom beam; and (S4) placing the modeled tiles or bottom beam, and then performing gel coat spraying plus 300 # fiber layer I plus 450 fiber layer II plus skeleton shaping processes. The method has the beneficial effects that by combining the material characteristics of the building, the glass fiber reinforced plastic material repairing cost is low, the consumed time is short, the effect is fast, the environmental pollution is small, the hardness is high, and the waterproof and anti-corrosion properties are good.