NOVELTY - Preparing hierarchy structure titanium dioxide powder comprises (a) mixing (S12) a first solution containing titanium dioxide precursor and water molecule necessary for hydrolysis of the precursor to form nano-sized crystalline titania powder, (b) reacting (S14) the nano-sized crystalline titania powder to form amorphous titanium dioxide powder, (c) aggregating (S16) amorphous titanium dioxide powder to sphere shape by sol-gel method, (d) adding a second solution for controlling a size of the aggregate in the hydrolysis, and (e) forming (S20) mesopore in the titanium dioxide powder.    USE - The hierarchy structure titanium dioxide powder is useful for fabricating a dye sensitized solar cell (claimed).    ADVANTAGE - The hierarchy structure titanium dioxide powder improves photoelectric conversion efficiency of the dye sensitized solar cell and reduces production cost of the solar cell. The size of the titanium dioxide aggregate can be easily controlled.    DETAILED DESCRIPTION - Preparing hierarchy structure titanium dioxide powder comprises (a) mixing (S12) a first solution containing titanium dioxide precursor and water molecule necessary for hydrolysis of the precursor to form nano-sized crystalline titania powder, (b) hydrothermally reacting (S14) the nano-sized crystalline titania powder to form amorphous titanium dioxide powder, (c) aggregating (S16) amorphous titanium dioxide powder to sphere shape by sol-gel method, (d) adding a second solution for controlling a size of the titanium dioxide aggregate in the hydrolysis, and (e) forming (S20) mesopore in the amorphous titanium dioxide powder. An INDEPENDENT CLAIM is included for manufacturing a dye sensitized solar cell comprising the steps (a)-(e) as above per se, forming a crystalline titanium dioxide electrode layer on a transparent conductive substrate, forming a porous titanium dioxide electrode layer on the crystalline titanium dioxide electrode layer using the hierarchy structure titanium dioxide powder, absorbing light-sensitivity dye molecule in the crystalline titanium dioxide electrode layer, and heat-treating and plasticizing the porous titanium dioxide electrode layer.    DESCRIPTION OF DRAWING(S) - The figure shows a flow chart of a method for preparing hierarchy structure titanium dioxide powder (Drawing includes non-English language text).    Amorphous titanium dioxide powder formation step (S10)    Mixing a first solution containing titanium dioxide precursor and water molecule necessary for hydrolysis of the precursor to form nano-sized crystalline titania powders (S12)    Hydrothermally reacting the nano-sized crystalline titania powders to form amorphous titanium dioxide powder (S14)    Aggregating amorphous titanium dioxide powder to sphere shape by sol-gel method (S16)    Forming mesopore in the amorphous titanium dioxide powder. (S20)