The invention provides a novel self-compensation A-shaped seal ring. The seal ring comprises a seal ring substrate as well as a stainless steel metal framework and an inflation cavity which are arranged in the seal ring substrate; the cross section of the seal ring substrate is in a shape similar to A, the cavity between one end of a cross beam and the tip part of A is the inflation cavity, the stainless steel metal framework is arranged in the cross beam and the other end of A, and the tip part, namely, the lip position, of the seal ring substrate has a non-symmetrical structure; an air inlet and an air outlet are formed in positions, in the cross beam of A at the two radial ends, of the seal ring substrate, and the air inlet and the air outlet are connected with an air inlet tube and an air outlet tube respectively; the inflation cavity is connected with the air inlet tube and the air outlet tube, certain pressure is maintained in the inflation cavity all the time to extrude the lip, and self-compensation is realized; the inner wall of the inflation cavity is coated with a polyethylene plastic film, and the air tightness of the inflation cavity is guaranteed. The seal ring can perform self-compensation on reduced contact pressure in a sealed contact region due to abrasion, and the service life of a seal component is greatly prolonged.