The invention relates to a preparation method of a titanium oxide nanoflower film, which comprises the steps of uniformly mixing tetrabutyl titanate, concentrated hydrochloric acid and deionized water at a volume ratio of (1-3):15:15 in a reaction kettle provided with a teflon lining, obtaining a clear reaction solution, placing washed FTO (Fluorine doped Tin Oxide) conductive glass in the solution obliquely, sealing the reaction kettle, and allowing the reaction kettle to react at 120-180 DEG C for 1-24h, washing a product after the reaction, drying, and obtaining the titanium oxide nanoflower film. The titanium oxide nanoflower film has hydrophilicity, the average thickness of the film is 10-300 micrometers, and the film is formed by petals with lengths of 1.3-3.2 micrometers and widths of 380-710nm. According to the method, an organic solvent, heavy metal ions or hypertoxic hydrofluoric acid is not used, and the method has the characteristics of low cost, and high safety and controllability. The fabricated titanium oxide nanoflower film is high in photocatalytic activity, and is expected to have wide application prospects in the fields of photocatalytic sterilizing materials, environmental pollution controlling, dye sensitization solar cells and the like.