The invention discloses a method for separating silicon dioxide in wollastonite raw ore. The method comprises the steps that the wollastonite raw ore is subjected to smashing, ball milling and magnetic separation to obtain a material A; water is added into the material A, the pH is adjusted, oxidized paraffinum sodium salt and stearic acid are added for flotation, and a material B is obtained; the material B is added into an oxalic acid solution with the pH being 1-3 after being calcined, and filtering, washing and drying are carried out to obtain a material C; the material C is added into water, ammonium chloride is added, ammonium chloride is added after microwave heating, the pH is adjusted to range from 0.6 to 1.2, and sol is obtained; a surface active agent is added into the sol, the pH is adjusted to range from 3 to 4, hydrochloric acid is added, the pH is adjusted to range from 0.6 to 1.2, and a material D is obtained; the material D, sodium fluoride, sodium hydroxide, hydrochloric acid and nitrilotrimethylene triphosphonic acid are added into water for a hydrothermal reaction. According to the method for separating silicon dioxide in the wollastonite raw ore, the steps are simple, and obtained silicon dioxide is high in yield and purity, good in stability and capable of being applied to multiple fields.