The invention discloses a ring seal structure provided with a seal surface extension portion. The ring seal structure structurally comprises a seal ring adjustment device, a mounting ring and a buckling groove. Based on the prior art, according to the ring seal structure, dimension control over an elastic seal layer is achieved through mechanical transmission; four one-way support fan-shaped plates are arranged in four directions of the elastic seal layer, and therefore, the effect that fluid is sealed can be well achieved; a magnetic mounting structure and a magnetic rotating mechanism can bedriven to rotate through control over an externally-arranged adjustment ring; and a transmission mechanism can be pushed to act on a contact ring structure, and thus, control over the seal dimensionsis achieved. The seal dimensions can be controlled according to actual conditions through drive of mechanical transmission; a seal ring assembly does not need to be replaced, and thus, seal structures of different sizes can be sealed rapidly; and operation is easy to conduct, people do not need to spend time for replacement, and work efficiency is improved.