The invention discloses a method of sealing circular seams of cable clamps on a main cable of a suspension bridge and relates to the technical field of cable protection. The cable clamps sleeve the main cable; a wedged seal made of rubber is provided; the wedged seal comprises a wedged body having one high end and the other low end; the low end of the wedged body is provided with a guide slope having a sloping angle a; the wedged body is provided with a plurality of positioning pin holes; the orientation of the positioning pin holes is perpendicular to that of a wedged face of the wedged body; the wedged face is provided with at least two hoop grooves facing in the same direction as the positioning pin holes; the wedged body is provided with a plurality of sealing protrusions extending out of the bottom of the wedged body. The method includes the steps of A, cutting the wedged seal; B, mounting an O-shaped seal ring; C, mounting the wedged seal; D, mounting two first hoops; E, mounting a waterproof jacket and a second hoop; and F, repeating the steps A, B, C, D and E. Compared with the prior art, the method has the advantages that full sealing is ensured for the circular seams of the cable clamps, the wedged seal rarely ages, and the wedged seal has a long life.