the present invention relates to a method for preparing self - assembled silicon nanotubes by a hydrothermal method . a method for preparing self - assembled sints comprises forming a mixture of silicon oxide and water in a sealed container , wherein the mixture has a silicon oxide to water ratio of no more than 10 % by weight . the mixture is maintained at a constant temperature and a constant pressure , and the mixture is stirred for a period of time . self - assembled sints may be formed with an average inner diameter of less than 5 nm and an average outer diameter of around 15 nm . the present invention completely utilizes non - toxic raw materials , and the materials and process do not pollute the environment , so the method satisfies the development trends of the modern industry .