The invention belongs to the technical field of preparation of titanium dioxide and in particular relates to a preparation method of anatase type titanium dioxide. Aiming at the problem that high-purity anatase type titanium dioxide cannot be prepared through an existing titanium tetrachloride gas-phase oxidization method, the invention provides the preparation method of the anatase type titanium dioxide; the preparation method comprises the following steps: a, pre-heating oxygen gas to be 850 DEG C to 1050 DEG C through a pre-heating furnace; pre-heating titanium tetrachloride to 750 DEG C to 950 DEG C through the other pre-heating furnace under the protection of inert gas; b, introducing the oxygen gas and titanium tetrachloride, which are pre-heated in the step a, and reacting; controlling reaction temperature to be 850 DEG C to 1050 DEG C and reaction time to be 2s to 15s; after reacting, collecting to obtain anatase type TiO2. According to the preparation method of the anatase type titanium dioxide, parameters are reasonably matched and the conversion from the anatase type TiO2 to rutile type TiO2 is inhibited, so that the high-purity anatase type TiO2 is obtained; the TiO2 has controllable granularity and high purity; the method provided by the invention has the advantages of simplicity in operation, less tail gas content and low cost and has important economic significance.