The invention provides a hole plugging device for a cable conduit, and aims to solve the problem that the cable conduit of which the hole is plugged with plugging mud/ concrete is unlikely to dismount in the prior art. The hole plugging device comprises a sleeve, a rubber ring, a stop block, a pressing block and an extrusion device, wherein the sleeve is sleeved on a cable, the stop block is fixedly connected to one end of the sleeve, the pressing block is arranged on the sleeve and can move along the axial direction of the sleeve, the rubber ring is sleeved on the sleeve and positioned between the stop block and the pressing block, and the rubber ring is provided with a closed inner cavity which is filled with fluid; one end of the sleeve is connected with a rubber tube, and the stop block and the rubber tube are respectively positioned at two ends of the sleeve. The pressing block and the sleeve extrude the rubber ring, so that the rubber ring is diffused towards the circumference to fill the clearance between the sleeve and the cable conduit, and the sleeve and the cable can be sealed by the rubber tube; the hole plugging device has a good sealing effect and is convenient to dismount; and the axial movement of the cable due to expansion with heat and contraction with cold or other reasons does not influence sealing.