NOVELTY - Preparing solar cell anti-reflective and self-cleaning composite thin film, comprises: (a) adding titanium sources into absolute ethyl alcohol and configuring; (b) adding acid solution into resulted ethyl alcohol mixing solution to obtain mixing solution (I); (c) mixing deionized water and absolute ethyl alcohol, adding an aqueous alcohol mixing solution to mixing solution (I) to obtain titanium dioxide solution; (d) mixing silicon precursor tetraethoxysilane and absolute ethyl alcohol to obtain silicon dioxide solution; and (e) mixing titanium dioxide solution with silicon dioxide solution.    USE - The method is useful for preparing solar cell anti-reflective and self-cleaning composite thin film.    ADVANTAGE - The composite thin film obtained by above method reduces cleaning of the outdoor solar cells and maintenance costs, and improves the utilization ratio of light by the cell, and is suitable for industrial process.    DETAILED DESCRIPTION - Preparing solar cell anti-reflective and self-cleaning composite thin film, comprises: (a) adding titanium sources into an absolute ethyl alcohol with volume ratio of 1:3-10, configuring ethyl alcohol mixing solution and stirring evenly; (b) after adding acid solution into ethyl alcohol mixing solution formed in the step (a) with volume ratio of 6-10:1 stirring for one hour, and obtaining mixing solution (I); (c) mixing deionized water with absolute ethyl alcohol to form mixing solution, then adding aqueous alcohol mixing solution to mixing solution (I) of the step (b), then stirring for one hour, and obtaining titanium dioxide solution, where the volume ratio of the titanium ions and the deionized water and the absolute ethyl alcohol is 3-10:10; (d) adding silicon precursor tetraethoxysilane into absolute ethyl alcohol, stirring the solution for one hour, then adding acid solution to regulate pH value to 2-3, then adding distilled water, where the ratio of silicon precursor and distilled water is 2-5:1, after stirring the solution for one hour, placing and aging for 12 hours, and obtaining silicon dioxide solution; and (e) mixing titanium dioxide solution obtained in the step (c) with silicon dioxide solution at mass ratio of 1-5:1 to form mixing solution, after spraying mixing solution to film, drying at 60 degrees C in vacuum situation, finally thermally processing at 300-500 degrees C for 1-6 hour, and obtaining solar cell anti-reflective and self-cleaning composite thin film.