The invention provides a preparation method of an anatase TiO2 monocrystal having a high-activity (110) face. The method comprises the following steps: 1, sequentially adding water, hydrofluoric acid and hydrogen peroxide to titanium powder, and stirring to obtain a titanium-containing solution; 2, reacting the titanium-containing solution in an autoclave at 120-220DEG C for 1-40h; 3, washing a reaction product obtained in step 2 with water and an organic solvent until the pH value is 6.5-7.5, and drying to obtain a solid; and 4, grinding the solid obtained in step 3, and calcining the ground solid at 120-900DEG C for 1-6h to obtain the anatase TiO2 monocrystal having a high-activity face. The preparation method has the advantages of low cost, simplicity, mild reaction, full utilization of above reaction raw materials, no generation of harmful gasses, and strong process repeatability.