The invention provides an inflaming retarding fiberglass material plate layer for manufacturing expansion joints and a preparing method and application of the inflaming retarding fiberglass material plate layer, and belongs to the technical field of composite materials. A bottom coating comprises a curing agent, first solvent-free mixed resin and first fire retardant. A structure layer comprises glass fiber, carbon fiber, second solvent-free mixed resin and a curing agent. A face coating comprises a nano abrasion resisting material, a UV ultraviolet screening agent, an additive, accelerant, third solvent-free mixed resin, second fire retardant and a curing agent. According to the preparing method, the bottom coating is sprayed to the surface of a model firstly, the structure layer is sprayed to the face, away from the model, of the bottom coating, then, the face coating is sprayed to the face, away from the bottom coating, of the structure layer, and the plate layer is obtained. The plate layer has good tenacity, meanwhile, the mechanical performance and the heat resisting performance are not changed, the oxygen index is very high, the flame spreading speed is very low, and self-extinguishment performance is achieved; and abrasion resisting performance and inflaming retarding performance are achieved, strength is high, the inflaming retarding fiberglass material plate layer canbe used for preparing various expansion joints, and the requirements of users are met.