NOVELTY - Preparation of nanotitanium dioxide film on surface of substrate guided by immobilized DNA, includes cleaning substrate and drying; immobilizing DNA on surface of substrate; and deposition and growth of nanotitanium dioxide by steeping the substrate by 2-20 mM titanium tetrachloride aqueous solution with hydrochloric acid (0.001-1 M), at 15-80 degrees C for 3-72 hours, steeping the substrate by ethanol solution of 2-10 mM butyl titanate at 15-90 degrees C for 1-72 hours, or steeping the substrate by ethanol solution of 2-10 mM isopropyl titanate at 15-90 degrees C for 1-72 hours.    USE - The method is for preparing nanotitanium dioxide film on surface of substrate guided by immobilized DNA, where substrate is monocrystal silicon sheet, glass sheet, ceramic sheet, functional plastic sheet, glass sheet plated with gold, or aluminum oxide sheet (claimed). The nanotitanium dioxide film can be used for preparing transparent conductive film of solar cell and component with automatic surface cleaning effect.    ADVANTAGE - The method is environment friendly; and guides assembly and growth of nanotitanium dioxide film on the surface at low temperature by using the substrate as template. The film formed by the method has crystal texture to a certain extent without sintering, and has uniform surface and strong adhesive attraction on surface of substrate.    DETAILED DESCRIPTION - Preparation of nanotitanium dioxide film on surface of substrate guided by immobilized DNA, includes:    (A) cleaning substrate and drying;    (B) immobilizing DNA on surface of substrate by (1) putting the substrate into organic solution with 0.5-10% amino silane, steeping for 30-180 minutes at 15-50 degrees C, forming self-assembled amino silane film, taking out the substrate, washing by cyclohexane, cyclohexane followed by water, methanol followed by water, or cyclohexane followed by ethanol, air drying, air or nitrogen blowing, and drying in vacuum at 80-120 degrees C for 30-90 minutes; (2) steeping the substrate by glutaric dialdehyde aqueous solution (1-3 vol.%) at room temperature for 0.5-1.5 hours, taking out, washing by distilled water, and drying by air or blowing; (3) taking deoxyribonucleotide oligomer, which has 12-35 bases, modifying one end by amino, and making a buffer solution with 5-10 mu m deoxyribonucleotide oligomer; and (4) steeping the substrate treated in step (2) by the solution formed in step (3) at 4-30 degrees C for 3-18 hours, taking out, washing, and airing; and    (C) deposition and growth of nanotitanium dioxide by steeping the substrate by 2-20 mM titanium tetrachloride (TiCl4) aqueous solution with hydrochloric acid (0.001-1 M), at 15-80 degrees C for 3-72 hours; steeping the substrate by ethanol solution of 2-10 mM butyl titanate at 15-90 degrees C for 1-72 hours; or steeping the substrate by ethanol solution of 2-10 mM isopropyl titanate at 15-90 degrees C for 1-72 hours.