The invention discloses a cable tightening device. The cable tightening device comprises a wire tightener and a wire clamp, wherein the wire tightener comprises a tightening rack, a movable press block and a press screw rod, the tightening rack comprises a guide rod, a connection part and a support seat, a guide cylinder is arranged on the movable press block and is matched with the guide rack, the wire clamp comprises a male clamp and a female clamp, the male clamp and the female clamp are respectively arranged on the movable press block and the support seat of the wire tightener, the movable press block can be driven to move relative to the support seat in a reciprocating way by rotating the press screw rod on the wire tightener, so that split cables are pressed and bonded by the male clamp and the female clamp; an anti-slip fixing device is arranged on the wire tightener, and the tightening device can be prevented from sliding to affect a cable fixing effect due to inclining or bending of the cable during operation; and at least two locking screw rods are arranged at two sides of the male clamp, the cables penetrate through between the locking screw rods at the two sides, the cables within a length range of the male clamp are simultaneously pressed, the split cables can be fixed and tightened by a combination of the male clamp and the female clamp, and a plurality of wire clamps are not needed to fixed at a plurality of points.