The invention discloses a device for protecting a J-shaped pipe out of an offshore wind power submarine cable. A centralized positioning protective device is arranged on the submarine cable at the tail of the J-shaped pipe, the submarine cable is tightly hugged by the centralized positioning protective device, and the centralized positioning protective device is clamped in the J-shaped pipe, so that the submarine cable is located at the central position of the J-shaped pipe; the tail of the positioning protective device is further connected with a bending protective device, the bending protective device adopts a joint occlusion structure, and a chain shape is formed by increasing the number of joints; a through hole is formed in the center of the bending protective device, and is used for penetrating through the submarine cable. According to the device, the protection of the submarine cable after coming out of the J-shaped pipe can be effectively solved, the submarine cable can be restricted to swing in the J-shaped pipe, overbending of the submarine cable in a suspension section is prevented, ocean current erosive wear as well as foreign object impact and anchoring damage are avoided, all of the installation is completed on a construction ship, the installation is simple, and in the construction aspect, later-stage maintenance is not needed after the installation is in place, so that the construction cost and later-stage maintenance cost are greatly reduced.