The invention discloses a mould box device of a straight wire-drawing machine. The mould box device comprises a through roll, a jin (jin is a Chinese character, meaning a well)-shaped frame, a mould box, a jack screw, an air pipe and an air pump, wherein the jin-shaped frame is arranged at a wire inlet end of the mould box, the jack screw is arranged at a wire outlet end of the mould box, the through roll is arranged at a wire inlet direction of the jin-shaped frame, the air pipe is connected with the air pump, the air pipe is provided with an opening at the jack screw, a sealing sheet is arranged at a roller part of the jin-shaped frame, and a rotating part of a stirrer in the mould box is provided with a sealing cover. According to the mould box device, the problem that wire-drawing powder does not enter the well-shaped frame is solved, the powder loading amount and the water loading amount of the mould box are increased, the circulation of water and powder is ensured; and by additionally providing an air cooling device, the problems that a steel wire is poor in cooling effect and water is carried on a winding drum is solved. The mould box device disclosed by the invention has the advantages of improving the cooling and lubricating effect of the steel wire, increasing the wire-drawing speed of the steel wire, and improving the production operability and the product quality.