NOVELTY - Preparing patterned composite film comprises (i) preparing titanium dioxide film by soaking glass substrate in absolute methanol solution, and adding glass substrate to the precursor solution containing titanium (IV) sulfide; (ii) preparing S-adenosyl-L-methionine (SAM) containing methyl or amino group patterned surface by adding titanium dioxide nano film into normal hexane solution, adding patterned substrate in absolute methanol; (iii) preparing copper sulfide patterned film by adding patterned SAM base plate in precursor solution.    USE - The patterned composite film is useful for enhancing light absorption of titanium dioxide film, and for solar battery, optoelectronic switch, optoelectronic converter and optical storage.    ADVANTAGE - The method improves the optical absorption intensity of the titanium dioxide nano film and expands the optical absorption wavelength range to enhance the solar absorption efficiency of the film by forming patterned micro structure copper sulfide/titanium dioxide composite film P-N hetero-junction.    DETAILED DESCRIPTION - Preparing patterned composite film, comprises (i) preparing titanium dioxide film by soaking glass substrate in absolute methanol solution of 3-aminopropyltriethoxysilane, keeping in room temperature, taking out, washing with absolute methanol and water, drying by using nitrogen, and then taking titanium(IV) sulfide, hydrogen peroxide and water to form precursor solution, adjusting pH to 1.6, adding glass substrate with 3-aminopropyltriethoxysilane to the precursor solution on the surface to deposit for 20-60 minutes at 70-80 degrees C; (ii) preparing S-adenosyl-L-methionine (SAM) containing methyl or amino group patterned surface by adding titanium dioxide nano film into normal hexane solution of octadecyltrichlorosilane, keeping in room temperature, taking out, washing with normal hexane, drying by using nitrogen, and then adding mask on the titanium dioxide nano film with octadecyltrichlorosilane on the surface, implementing ultraviolet lighting, which changes octadecyltrichlorosilane SAM of exposure area with hydroxy group to obtain SAM containing hydroxy or methyl group patterned surface, adding SAM containing hydroxy or methyl group patterned substrate in absolute methanol solution of 3-aminopropyltriethoxysilane, and keeping in room temperature; (iii) preparing copper sulfide patterned film by adding patterned SAM base plate in precursor solution comprising copper sulfate, sodium thiosulfate and EDTA, adjusting pH to 1-3, depositing twice at 65-75 degrees C for 0.5-1 hour each time, finally burning copper sulfide film under the protection of nitrogen gas atmosphere at 200-300 degrees C to obtain nano copper sulfide patterned film with integrated pattern, clear edge and tight structure on the surface of titanium dioxide nano film.