NOVELTY - A thin titanium dioxide layer preparing method involves cleaning fluorine-doped tin oxide conductive glass in acetone, ethanol and deionized water in ultrasonically, and storing in ethanol, followed by adding tetrabutyl titanate in the mixed solution of concentrated hydrochloric acid and deionized water to perform hydro-thermal reaction to prepare a multistage structure titanium dioxide nano-colloid by adding polyethylene glycol. The nano-colloid is coated on rotary electric conductive glass surface, followed by spin-coating lead iodide solution and methyl iodide solution, and drying.    USE - Method for preparing thin titanium dioxide layer of perovskite cell.    ADVANTAGE - The method enables preparing thin titanium dioxide layer with wide photoresponse rang, enhanced light scattering, improved capture of light, increased utilization ratio of sunlight, high conversion efficiency, and is cost-effective.    DETAILED DESCRIPTION - A thin titanium dioxide layer preparing method involves utilizing cell structure comprising perovskite conductive glass, titania thin, and perovskite structure layer, cleaning fluorine-doped tin oxide conductive glass in acetone, ethanol and deionized water in ultrasonically, and storing in ethanol as an alternate conductive substrate, followed by mixing concentrated hydrochloric acid and deionized water at a volume ratio of 1:1 to obtain mixed solution, and adding tetrabutyl titanate in the mixed solution at a volume ratio of 1:10 to perform hydro-thermal reaction to prepare a multistage structure titanium dioxide nano-colloid by adding polyethylene glycol. The nano-colloid is coated on rotary electric conductive glass surface at a rotary coating speed of 2000 rpm to thickness of 200-500 nm. The coated glass is spin-coated with lead iodide solution at a rotary coating speed of 2000 rpm to thickness of 100-300 nm, and dried at 80 degrees C for 2 minutes, followed by coating methyl iodide solution on the lead iodide at a spin coating speed of 2000 rpm to thickness of 100-300 nm, and drying at 80 degrees C for 2 minutes to obtain finished product.