The utility model discloses a novel breaking of contact case mounting structure of transformer substation's assembly type structure lightning protection, including H shaped steel, the assembled wallboard is connected on the edge of a wing of H shaped steel, fixedly connected with adopts the breaking of contact box that composite insulating material made on H shaped steel, it has the through -holeto connect the prefabrication of breaking of contact position of the case body or process at H shaped steel, the breaking of contact box passes through bolt and H shaped steel fixed connection, earthing device in the breaking of contact box extends to card case outside, and this earthing device snap -on is on H shaped steel, be equipped with the electric installation that draws that causes the electricity in the breaking of contact box horizontal ground net on the breaking of contact box. The utility model provides an earthing conductor be connected the problem with the mistake between the old-fashioned casing steel sheet, ensure the insulation between earthing conductor and the casing. And partial band steel bending section exposes not pleasing to the eye problem outside, can ensure thestability of breaking of contact case installation.