The present invention discloses a box, comprising: a box body; a box cover, wherein the box cover is covered at an opening of the box body, a limiting cylinder is formed on the bottom end of the box cover near an outer edge, and the bottom end of the box cover is provided with an annular clamping groove located at the outer side of the limiting cylinder; an elastic sealing ring which comprises: a top sealing ring, an inserting flange; a middle sealing cylinder, and the middle sealing cylinder is sleeved on the outer cylinder wall of the limiting cylinder; and a bottom sealing ring, and the outer edge of the bottom sealing ring is in compression sealing contact with the inner wall of the box body.