The utility model relates to a modular reducing waterproof cable hole shutoff forming device has the bottom plate, and the middle part of bottom plate is equipped with the cable hole, and both sides respectively are equipped with the draw -in groove of horizontal mutual disposition about the cable hole of bottom plate, and each cartridge of both ends has a slide about two draw -in grooves, and thefront end of two slides all is equipped with the arc cutting ferrule, and the rear end of two slides all is equipped with transfers knothole, and the cable hole each side of bottom plate is equippedwith a locating hole, and the locating hole of bottom plate both sides matches with the accent knothole on the homonymy slide, the utility model discloses simple structure, convenient to use, the installation is dismantled quick conveniently, can be effectual carries out the shutoff to the cable hole, has safe and reliable, the shutoff is tight, waterproofly prevents that the toy performance is good, overhauls advantages such as convenient. Receive and release the convenience, installation transportation is convenient, and occupation space is little, and within 10 seconds, no matter topography, weather, anytime and anywhere expandes the use.