The utility model relates to an overhead hoisting device for a transformer substation, in particular to a portable overhead hoisting device special for a BBG1-12/300 type transformer substation. The portable overhead hoisting device comprises a horizontal base, wherein a bearing block is arranged at the upper part of the horizontal base and is matched with an upright post through a flange; a horizontal suspension arm is arranged at the upper part of the upright post; and an electric block is fixed on the horizontal suspension arm. The portable overhead hoisting device has a simple and unique structure and high replacing and mounting efficiency, is not easy to injure personnel and equipment and is suitable for the BBG1-12/300 type transformer substation.