The invention discloses a high-airtightness and high-strength methane tank cover. The high-airtightness and high-strength methane tank cover comprises a casing, wherein fixed clamping parts and movable clamping parts are arranged at the upper end and the lower end of the side wall of the casing respectively; an outer cover body cavity, a steel ring cavity and an inner cover body cavity are arranged in sequence in an inner cavity of the casing; the radiuses of the outer cover body cavity, the steel ring cavity and the inner cover body cavity are successively decreased; and an outer cover body, a steel ring and an inner cover body are successively arranged in the outer cover body cavity, the steel ring cavity and the inner cover body cavity. According to the invention, the fixed clamping parts and the movable clamping parts are arranged at the upper end and the lower end of the side wall of the casing respectively, and used in a matched state, so that the waste of resources caused by leakage of generated gases from the lateral side of the methane tank cover can be effectively prevented, furthermore, an added fixed steel ring and a sealing washer which is matched with the fixed steel ring can effectively prevent the gas leakage from the inside of the methane tank cover. A multi-cover body structure is used and reinforcing ribs are arranged on the cover body, so that the use intensity of the methane tank cover is increased to meet needs of people.