Disclosed are a method and apparatus for decolorization of reactive anthraquinone dye-containing wastewater using photocatalytic oxidation, which include inducing high-efficiency photocatalytic oxidation under a controlled salt concentration and pH of wastewater to perform effective decolorization of reactive anthraquinone dye-containing wastewater. The method for decolorization of reactive anthraquinone dye-containing wastewater using photocatalytic oxidation, includes: introducing a photocatalyst and salt into reactive anthraquinone dye-containing wastewater and adjusting pH of the wastewater to a level higher than neutral pH; and irradiating UV to the photocatalyst to carry out cleavage of the reactive anthraquinone dyes through photocatalytic oxidation, thereby accomplishing decolorization of wastewater.