A clamp structure for an underwater control cable comprises an arc-shaped upper cover and an arc-shaped lower cover which are arranged oppositely. The two ends of the upper cover are provided with a rotating structure and a clamping structure respectively, and the two ends of the lower cover are provided with a rotating structure and a clamping structure respectively. The arc-shaped upper cover and the arc-shaped lower cover are correspondingly buckled together and connected together to form a cylindrical cover body with a cavity inside. Each rotating structure comprises a rotating shaft, and multiple sets of connecting plates connected to the rotating shaft in a pivoting mode and arranged in a cross mode. The connecting plates which are arranged in the cross mode are connected with one end of the upper cover and one end of the lower cover. The upper cover and the lower cover are opened and closed around one common rotating shaft. Each clamping structure comprises two horizontal end plates connected to one end of the upper cover and one end of the lower cover respectively, wherein the upper cover and the lower cover are connected into a whole in a butt joint mode by means of the two horizontal end plates through a bolt and a nut. The control cable is fixed through the upper cover, the lower cover and the clamping structures, the control cable is prevented from swinging underwater, and the probability of friction damage between the control cable and the main structure is eliminated.