The present invention discloses a seabed fixing device based on a dynamic cable system, including a dynamic cable fixing device, a dynamic cable bending holding device, an H-shaped steel reinforcing rib, a high strength steel pipe framework, a dynamic and static cable connector box and so on, the high strength steel pipe framework forms a main body bearing frame structure, and brackets of the main body bearing frame structure are connected and fixed by H-shaped steel reinforcing ribs, the dynamic and static cable connector box connecting a dynamic cable and a static cable is disposed on a base of the main body bearing frame structure, the dynamic cable blending holding device, a dynamic cable holding device and a bending limiter fixing mechanism for avoiding upward bending of the cables when the cables are under a tensional force, are disposed at a side of the dynamic and static cable connector box at which the dynamic cable has disposed, the brackets of the main body bearing frame structure are connected to extension brackets under the brackets of the main body bearing frame structure by connecting flanges. The device of the present invention is used for fixing the seabed dynamic cable, isolating the force of the dynamic cable and the static cable, and bearing the tensile force received by the dynamic cable, and protecting the static cable from being pulled to the seabed to undergo unintentional damage, and can prevent the dynamic cable system from breaking down.