Abstract: Disclosed relates to a method of manufacturing plastic reinforced by flame retardant fibers. The method of manufacturing plastic reinforced by flame retardant fibers includes: a) mixing a thermosetting resin containing a methylol group and an inorganic flame retardant material, and introducing a solvent to disperse the mixture and then diluting the mixture with water, thereby manufacturing an aqueous resin solution; b) immersing flame retardant fibers in the aqueous resin solution; c) drying the immersed flame retardant fibers; d) forming the dried flame retardant fibers; and e) cooling the formed plastic.