A titanium dioxide nanorod having anisotropy and a preparation method thereof in which, particularly, an ultrafine composite fiber of polymer and titanium dioxide precursor and a single crystal titanium dioxide nanorod using a phase separation are prepared, wherein a mixed solution containing titanium dioxide precursor, polymer which is compatible with the precursor and solvent is prepared, the mixed solution is electrospun to form titanium dioxide polymer composite fiber containing ultrafine fibril structure therein by the phase separation between the titanium dioxide precursor and the polymer, the composite fiber is heat-pressed, and the polymer material is removed from the composite fiber, so as to obtain titanium dioxide nanorod, which can be used as dye-sensitized solar cells, various sensors, and photocatalysts.