The utility model relates to a novel cable core fastening ring plug device which comprises a power source, a connection transition part, an execution part, a sleeve tube (7) and a fastening ring (8). The power source is a hydraulic pump. The execution part comprises a single-acting hydraulic cylinder (4) and a push tube (9). The hydraulic pump provides power to the single-acting hydraulic cylinder (4) in the execution part. The single-acting hydraulic cylinder drives the push rube (9), and the plugging effect of a cable core fastening ring (11) is realized. The transition connection of the single-acting hydraulic cylinder and the front end sleeve tube (7) can be realized through the connection transition part. The hydraulic cylinder loads the axial applied force suffered by the sleeve tube to a pull rod (3) through connection flanges (2) and (5), the pull rod (3) and auxiliary clamp plates (1) and (6). According to the device, the traditional mode of manually rotating a screw rod is changed, the plugging process of the cable core fastening ring by the push cylinder is realized, the defects of the cooperative operation of existing equipment by multiple people and low efficiency are overcome, and the device has the advantages of simple and compact structural design, small size, convenient carry, easy replacement of wearing parts and low cost.