The invention discloses a movable ring base of a mechanical sealing device. The movable ring base comprises a movable ring base body (1); the movable ring base body (1) is provided with a movable ring sleeving cavity (3) for sleeving a movable ring (2); multiple first radial convex edges (4) are peripherally distributed at the edge of the movable ring base body (1); a second radial convex edge (5) is arranged on the edge of the movable ring base body (1) between the first radial convex edges (4); the outer diameter of the second radial convex edge (5) is smaller than the outer diameters of the first radial convex edges (4); the second radial convex edge (5) is connected with the side part of one adjacent first radial convex edge (4), and has a spacing distance from the other adjacent first radial convex edge (4); and straight transmission inner walls (3.1) are peripherally distributed on the inner side wall of the movable ring sleeving cavity (3). The movable ring base can effectively shorten the axial assembly length, and can transfer the torque.