The invention discloses a preparation method of titanium dioxide microspheres in poly-crystal face platy-monocrystal structures and relates to a preparation method of a nano material. The preparation method comprises the following steps: adding a fluorine containing reagent into a titanyl sulfate aqueous solution to prepare a precursor aqueous solution with the molar ratio of fluorine and titanium of (16:1) to (24:1); adding the precursor aqueous solution into a reaction kettle in a volume ratio of the precursor aqueous solution and the reaction kettle of 7:10, insulating and incubating for 12 hours at 180 DEG C and cooling to obtain a reactant; carrying out suction filtration on the reactant, and after the obtained filter cake is washed and sucked by deionized water, placing in a vacuum drying box to be dried and taken out; and after calcining the obtained filter cake in a ceramic boat in a muffle furnace at 450 DEG C, cooling to room temperature to obtain white powder so as to obtain the titanium dioxide microspheres in poly-crystal face platy-monocrystal structures. The titanium dioxide microspheres prepared by the preparation method disclosed by the invention are in smooth dehorned octahedral anatase titanium dioxide monocrystal structures. The side lengths of the titanium dioxide microspheres are 1.3-3.2 mu m and the thicknesses of the titanium dioxide microspheres are 0.6-1.0 mu m.