The invention discloses a salt treatment method for preparing anatase titanium dioxide, which adopts metatitanic acid obtained from the titanium slag with high acid soluble as the main raw material, particularly the metatitanic acid obtained from the hydrolysis of titanium slag and titanium liquid; and adopts phosphoric acid and sylvite as a salt treatment agent. The method obtains high-quality anatase titanium dioxide by pulping the metatitanic acid, adding the salt treatment agent, filtering and calcining the metatitanic acid treated by slat. The method improves the quality of the titanium dioxide product by controlling the addition of the slat treatment agent. The method based on the invention has the advantages of simple process, low cost and obvious economic and social benefits.