The invention discloses a gas storage tank with adjustable capacity. The gas storage tank comprises a lower sealing plate and an upper sealing plate located on the upper side of the lower sealing plate, first hinge rods are hinged to the lower end face of the upper sealing plate, the first hinge rods are arranged symmetrically left and right, second hinge rods located on the lower side of the first hinge rods are hinged to the upper end face of the lower sealing plate, the second hinge rods are arranged symmetrically left and right, the second hinge rods are hinged to the first hinge rods, theouter surfaces of the first hinge rods and the second hinge rod are connected with sealing cloths, the sealing cloths and the upper sealing plate and the lower sealing plate are closed to form a gasstorage cavity. According to the gas storage tank, the problem that the volume of the traditional gas storage tank is fixed is solved, due to the fact that the volume is fixed, the gas storage tanks with different volumes needs to be produced; the volume in the gas storage cavity can be increased according to actual needs, the same gas storage tank can provide different volumes, if gas leakage occurs in the gas storage tank, the gas storage tank can be temporarily closed by the self-belt sealing device, and potential safety hazards caused by gas leakage of the gas storage tank are avoided.