The invention belongs to the technical field of detection of high-pressure containers, and discloses an oil and water removing method on an inner surface of a high-pressure container and a detecting method. The oil and water removing method on the inner surface of the high-pressure container and the detecting method comprise detection and confirmation of grinding quality of the inner surface of the high-pressure container, solution anti-rusting cleaning agent cleaning, anhydrous ethanol cleaning, oil content detection, blowing and replacement. The high-pressure container, treated by the technical scheme, is excellent in inner surface quality; the contents of water and oil in the high-pressure container both satisfy the requirement of high-purity gas with a filling purity not lower than 99.99%; when the treated and detected high-pressure container is selected to fill the high-purity gas, the purity and long-time stability of the gas can be effectively guaranteed; and meanwhile, the quality of the high-purity gas is guaranteed, and the gas pollution degree is largely reduced.