TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The transparent aqua-based nano sol-gel composition comprises (wt.%): transparent aqua-based zeolite sol-gel (0.1-10, preferably 0.1-5), polysiloxane derivate (0.001-7, preferably 0.01-3), surfactant (0.001-5, preferably 0.01-3), and transparent aqua-based photocatalytic sol-gel of titanium dioxide (0.1-1.5, preferably 0.1-1). Preferred Method: In the step (2), the transparent aqua-based nano sol-gel is evenly applied to the surface of the transparent substrate with any wet coating method selected from a roll coating method, a wipe coating method, a brush coating method, a dip coating method, a spray coating method, a spin coating method and a sprinkle coating method. In the step (2), the coating film is cured with natural air drying for greater than or equal to 24 hours, or heating at less than or equal to 450 degrees C or for greater than or equal to 5 minutes. The method can be carried out to coat one side or both sides of the substrate. The dry film thickness of the finished transparent aqua-based coating film is 40-350 nm. Preferred Components: The polysiloxane derivate is selected from methyltrimethoxysilane, methyltriethoxysilane, ethyltributoxysilane, trimethyldiethyoxysilane, dimethoxymethylphenylsilane, triethoxypropylsilane, tripropoxypropylsilane and tributoxymethylsilane. The surfactant is selected from polyoxyethylene p-octylphenol ether, polyoxyethylene p-octyl laurate, polyoxyethylene sorbitol laurate, polyoxyethylene oleoyl ether, polyoxyethylene stearyl ether, polyoxyethylene sorbitan laurate and oleic diethanol amide. The transparent substrate is selected from glass and plastic substrate (preferably transparent glass, transparent polycarbonate resins, transparent polymethacrylate resins, transparent polystyrene resins and transparent epoxy resins). EXAMPLE - A transparent aqua-based nano sol-gel comprising (wt.%): transparent aqua-based zeolite sol-gel (0.1), methyltrimethoxysilane (0.0001) as polysiloxane derivate, polyoxyethylene p-octylphenol ether (0.0001) as non-ionic surfactant, transparent aqua-based photocatalytic sol-gel of titanium dioxide (0.1), and de-ionized water was prepared, by well mixing and then filtering the materials. The transparent aqua-based nano sol-gel was applied to surface of extra-white glass having the thickness of 5 mm by a dip coating method to form a transparent coating film (test) having thickness of 40-50 nm. An uncoated glass was used as comparative. A comparison of the self-clean property between the coated glass and the uncoated glass was carried out. The surfaces of both the coated glass and uncoated glass were firstly cleaned, and then the contact angle of a droplet on the two pieces of glass was measured at 35 degrees . Oleic acid was spread upon the surfaces of the coated glass and the uncoated glass to simulate the contamination on the glass, and then the contact angle of a droplet was again measured, which was now about 67 degrees . The two pieces of contaminated glass were exposed to the irradiation of UVA light (1 mW/cm2) for 24 hours, and the transmittance and contact angle of the two pieces of contaminated glass were measured at each period. The coating films having different thicknesses were formed on the surfaces of glass substrates by coating method. The pieces of coated glass were then cured under different conditions, and the self-cleaning property was measured. Variation in contact angle of oleic acid contaminated surface after 24 hours of UVA exposure was measured. After 24 hours, variation in contact angles ( degrees ) of oleic acid of test/control surfaces were 8/67, respectively. The lower contact angle indicates a better self-cleaning property. Thus, the coated surface showed better self-cleaning property.