NOVELTY - A self-cleaning collector tube antireflection film preparing method involves preparing colloidal sol-A by mixing isopropanol, ethyl orthosilicate and deionized water to obtain mixture. The pH of the mixture is adjusted by stirring hydrochloric acid, and subjected to aging. The resultant mixture is added with polyethylene glycol to obtain colloidal sol-A, followed by preparing colloidal sol-B, soaking a substrate in the sol-A by fixing in vertical position, and performing liquid sedimentation. The substrate with the sol-A is completely separated, dried and heated. The temperature is reduced.    USE - Method for preparing self-cleaning collector tube antireflection film that is utilized in power generation type solar energy heat collecting tube.    ADVANTAGE - The method enables preparing the film with high light transmittance, improve collector tube photothermal conversion rate, anti-reflective hydrophobic and photocatalytic properties, in a simple, easy and inexpensive manner.    DETAILED DESCRIPTION - A self-cleaning collector tube antireflection film preparing method involves preparing colloidal sol-A by mixing isopropanol, ethyl orthosilicate and deionized water according to the deionized water and ethyl orthosilicate volume ratio of 0.6:1, and ethyl orthosilicate and isopropyl alcohol volume ratio of 1-3:20 to obtain mixture. The pH of the mixture is adjusted to pH 4-5 by stirring hydrochloric acid for 1-2 hours, and subjected to aging for 6-8 hours. The resultant mixture is added with 20-30 g polyethylene glycol with molecular weight of 1000 per liter of isopropanol and stirred for 1-2 hours to obtain colloidal sol-A, followed by preparing colloidal sol-B by mixing isopropanol, tetraethyl orthosilicate, tetrabutyl titanate, ethyl acetoacetate and deionized water according to the isopropanol, tetraethyl orthosilicate, tetrabutyl titanate and ethyl acetoacetate volume ratio of 20:8-10:1-3:1.2, and ethyl orthosilicate and deionized water volume ratio of 1:1 to obtain mixed liquid. The pH of the mixed liquid is adjusted to 4-5 by adding hydrochloric acid and stirring at room temperature for 1-2 hours. The mixed liquid is subjected to aging for 6-8 hours to give a colloidal sol-B, followed by soaking a substrate in the sol-A by fixing in vertical position, performing liquid sedimentation at a uniform speed of 1.6-2.5 mm/s to achieve uniform sedimentation of the sol-A. The substrate with the sol-A is completely separated and dried to adhere the sol-A to the surface of the substrate. The substrate is heated to 380-420 degrees C for 20-30 minutes. The temperature is reduced to room temperature. The substrate is dipped to the sol-B and fixed in vertical position, followed by performing liquid sedimentation at a uniform speed of 1.6-2.5 mm/s to achieve uniform sedimentation of the sol-B. The substrate with the sol-B is completely separated and dried to adhere the sol-B to the surface of the substrate. The substrate is heated to 380-420 degrees C for 20-30 minutes to obtain finished product.