The utility model relates to a cable branch box filled with insulation medium, which separately sends electricity to the user through the branch box by the main cable, belonging to a technical field of the electric force distribution equipment. The cable branch box filled with insulation medium is mainly that box body is provided with three sets of single-phase upright cylinders, and the structure of each set of upright cylinder is identical. The utility model is characterized in that the bus-bar room of the upper part of the branch cylinder body is provided with a metal short circuit ring, a cable contact is connected with the metal short circuit ring, the cable head room of the lower part of the cylinder body is provided with a cable head, the cable is connected with the cable head contacted with the cable contact, and the branch cylinder body is filled with the insulation medium of gas SF6. The utility model has compact and reasonable structure, reliable electrically connection and insulation, stable capability, small volume. Because the branch cylinder body is filled with the insulation medium of gas SF6, the insulation of the cable head and the metal cylinder wall can satisfy the operating requirement. Because three sets of single-phase upright cylinders constitute the structure of one ingress and two out or one ingress and multiple out, the magnetic field of the cylinder body is zero. Because a manometer and components of valve are installed out of the branch cylinder body, the operation is safe.