The present invention relates to a method for preparing anatase-type titanium dioxide (TiO2) nanoparticles, the method comprising the steps of: uniformly mixing titanium n-butoxide and cetyltrimethyl ammonium salt (CTAS) in water; subjecting the mixture to hydrothermal treatment at a temperature of 60˜120° C.; and collecting anatase-type titanium dioxide nanoparticles produced by the hydrothermal treatment and drying the collected nanoparticles. According to the present invention, anatase-type titanium dioxide nanoparticles having excellent crystallinity can be easily prepared in large amounts by a simple process without needing heat treatment.