Storage tank is a steel sealed container used to store liquid or gas. Storage tank engineering is an essential and important infrastructure in petroleum, chemical industry, grain and oil, food, fire fighting, transportation, metallurgy, national defense and other industries, and its basic requirements are also quite strict. Foundation soil to meet the design value of bearing capacity requirements, but also to do anti-seepage moisture-proof treatment, otherwise leakage will cause serious pollution to the environment, underground water vapor, it will corrosion steel tank. Therefore, composite HDPE geomembrane is an indispensable anti-seepage and moisture-proof material in tank foundation design. It pastes geotextiles on one or both sides of the film to form a composite geomembrane. Its form has a cloth a film, two cloth a film, two film a cloth. Geotextile as a protective layer of geomembrane, so that the protective impermeable layer is not damaged. To reduce ultraviolet radiation, increase anti - aging performance, had better use buried method laid.