The invention discloses a method for purifying a high-molecular-weight brominated epoxy fire retardant through a solution crystallization process. The method comprises the following steps: mixing brominated epoxy base resin with a pre-added solvent, adding tetrabromobisphenol A, stirring for dissolving, adding a catalyst, carrying out reflux reaction for 0.5-4 hours at 120-250 DEG C, dropwise adding the solvent, stirring and mixing for 0.5-3 hours at 80-150 DEG C, cooling the product to be between room temperature and 80 DEG C, filtering to prepare a crude product, crushing the crude product and drying the crude product in vacuum to prepare a finished product. The method is simple and convenient and is high in effect; the brominated epoxy is purified by the solution crystallization process, so that the content of low polymers in the high-molecular-weight brominated epoxy fire retardant is lower than 0.3%; the appearance of the high-molecular-weight brominated epoxy fire retardant is non-transparent white crystal powder.