The invention relates to a method for preparing micro-nano-TiO2 spherical particles and prepared spherical particles. The method comprises the following steps: adding heptanoic acid into anhydrous ethanol, uniformly mixing, and adding titanium ester; stirring for 0.5-2 hours at 10-50 DEG C; adding water, and continuously stirring for 1-3 hours; separating to obtain a precipitate, washing the precipitate, and freeze-drying the precipitate; calcining the precipitate at 300-700 DEG C to obtain the micro-nano-TiO2 spherical particles. The micro-nano-TiO2 spherical particles prepared by the method are uniform in particle size distribution, regular in morphology, high in degree of crystallinity, high in dispersion and high in product purity; the preparation method is easy in operation, environment-friendly, mild in reaction conditions, low in energy consumption and easy to popularize.