The invention provides a decompression die-casting production line, wherein the automatic transportation of a suction box and a sand box toward their respective workstations is low in cost and high in efficiency. The decompression die-casting production line comprises a main circulation production line formed by a first conveying production line (L1) for conveying a suction box equipped with dies, a second conveying production line (L2) for conveying a sand box arranged inside the suction box, and a third conveying production line (L3) for conveying the suction box equipped with dies. The decompression die-casting production line also comprises a fourth conveying production line (L4) for conveying upper and lower dies, a fifth conveying production line (L5) for conveying upper and lower dies provided from a cooling region, a sand box conveying production line (L6) for guiding an empty sand box after being splitted up, and a flat conveying production line (L7) for guiding a flat guided together with the empty sand box to a die-clamping position (S9). The above production lines are formed by stepping conveyors (WB), traversers (TR) and the like.