A seal structure, comprising: a base body being a flat and wide strip with a predetermined thickness; a protruding portion disposed on a sealing surface of the base body for sealing and configured to be a strip boss which protrudes outwardly relative to the sealing surface and extends along a length direction of the base body; a deforming portion disposed on the sealing surface and configured to protrude outwardly relative to the sealing surface and extend along the length direction of the base body, the deforming portion having an extension length which is same as that of the protruding portion, and a protruding height which is larger than that of the protruding portion; and a connection through-hole suitable for a connecting piece (20, 30) including a bolt passing through, the connection through-hole being disposed between the protruding portion and the deforming portion and passing through the base body along a thickness direction of the base body, a plurality of the connection through-holes being disposed spaced from each other along the length direction of the base body; characterized in that, at first the height of the deforming portion elastically decreases when the deforming portion suffers a force towards the sealing surface generated by the connecting piece (20, 30), and then the connecting piece (20, 30) comes into contact with the upper surface of the protruding portion, and the protruding portion is deformed to a lesser extent than the deformation of the deforming portion due to said force, such that the upper surface of the protruding portion is in tight contact with the inner surface of the connecting piece (20, 30), and a part of an outside surface of the deforming portion is in tight contact with the inner surface of the connecting piece (20, 30) because of elastic deformation. a base body being a flat and wide strip with a predetermined thickness; a protruding portion disposed on a sealing surface of the base body for sealing and configured to be a strip boss which protrudes outwardly relative to the sealing surface and extends along a length direction of the base body; a deforming portion disposed on the sealing surface and configured to protrude outwardly relative to the sealing surface and extend along the length direction of the base body, the deforming portion having an extension length which is same as that of the protruding portion, and a protruding height which is larger than that of the protruding portion; and a connection through-hole suitable for a connecting piece (20, 30) including a bolt passing through, the connection through-hole being disposed between the protruding portion and the deforming portion and passing through the base body along a thickness direction of the base body, a plurality of the connection through-holes being disposed spaced from each other along the length direction of the base body; characterized in that, at first the height of the deforming portion elastically decreases when the deforming portion suffers a force towards the sealing surface generated by the connecting piece (20, 30), and then the connecting piece (20, 30) comes into contact with the upper surface of the protruding portion, and the protruding portion is deformed to a lesser extent than the deformation of the deforming portion due to said force, such that the upper surface of the protruding portion is in tight contact with the inner surface of the connecting piece (20, 30), and a part of an outside surface of the deforming portion is in tight contact with the inner surface of the connecting piece (20, 30) because of elastic deformation.