The utility model discloses a 12kV current -carrying 1250A solid insulation cubical switchboard, the power distribution box comprises a box body, the box middle part is provided with insulating square tubular, be provided with vacuum switch, isolator, earthing switch in the insulating square tubular respectively. Insulating square tubular outside is equipped with the metallic shield ground plane, spring stored energy operating device, blocked mechanical system set up in insulating square tubular one side, are connected with vacuum switch, isolator, earthing switch drive respectively. The utility model discloses an adoption link up bus structure tied in a bundle, no matter works a telephone switchboard in the front and back end of business turn over linear system interconnected system, can both ensure sufficient electrically conductive cross -section, adopts the watchband to touch the finger technique, contact evenly distributed, and reduction conductor length reduces whole loop resistance, avoids the inhomogeneous conduction problem in the heavy current electrical contact, and the crimping that the solution conductor is aroused by heat altered shape is unreal to and the pernicious deformations problems that generates heat who from this further arouses. Make 12kV solid insulation cubical switchboard rated current grade reach 1250A.