A method for preparing self-cleaning, water- and dirt-repellent coating on a substrate, which comprises the steps of: stirring a mixture of polymer resin, curing agent and aqueous solvent at a speed of 300 to 350 rpm, at room temperature, under a pressure of 1 standard atmosphere, for a duration of 1 hour; exposing the mixture to ultrasound, at a temperature of 20 degree Celsius, for a duration of 20 minutes; applying a thin layer of the mixture on the substrate; and drying the coated substrate at room temperature for a duration of 5 minutes to 24 hours. Also provided is a self-cleaning, water- and dirt-repellent coating prepared on a substrate by the above-mentioned method.