Disclosed is a method of preparing high crystalline nanoporous titanium dioxide, in which the high crystalline nanoporous titanium dioxide, which is harmless to the human body and self-purified through the decomposition of organic matters, is prepared in mass production at the room temperature through a simply synthesis method. The method includes the steps of (a) mixing a titanium precursor and a surfactant in a solvent and performing a sol-gel reaction at a room temperature; (b) maturing a reactant obtained through the sol-gel reaction at the room temperature; (c) filtering the matured reactant and washing the matured reactant; and (d) drying the washed reactant to obtain titanium dioxide having nanopores.