The invention discloses a submarine cable center positioning and protection device, and the device comprises a guide cone, a conical ring, a positioning shaft, and a connecting shaft. The guide cone consists of two symmetric parts, and the head part of the guide cone is in a conical structure. The conical ring consists of two symmetric parts, wherein an outer side surface of the conical ring is in a conical structure, and an end face of the conical ring is provided with an annular through hole. The positioning shaft consists of two parts, wherein an external surface is provided with a reinforcing rib, and two side edges are provided with side plates. The side plates are provided with bolts holes, and the symmetric parts of the positioning shaft are connected through the bolt holes and bolts. Moreover, the guide cone, the conical ring and the positioning ring are connected through bolts. The connecting shaft consists of two symmetric parts, wherein the head part of the connecting shaft is provided with a connecting flange, and two side edges of the connecting shaft are connected with the side plates. According to the invention, the device can enable a cable at a lower port of a protection tube to be limited at the center of the protection tube, can effectively control the swinging of a submarine cable in the protection tube, prevents the submarine cable to collide with the rigid protection tube, and avoids the fatigue damage of the submarine cable under the long-term action of ocean current. Meanwhile, the device is simple in structure, is convenient to install, is high in reliability, and is long in service life.