The bar and wire rolling mill gearbox is a bar and wire rolling mill composite gearbox with compact structure, small footprint and high space utilization. The structure includes a box body, which is equipped with an input shaft and an output shaft that rotate at both ends supported by bearings in the box body. A power transmission gear pair is arranged between the input shaft and the output shaft, and the vertical output shaft of the input shaft is arranged on the top of the box body. A plurality of intermediate shafts are also added between the input shaft and the output shaft, and both ends of the intermediate shaft are supported on the bearings in the box body, and each intermediate shaft is parallel to the output shaft; a bevel gear pair for power transmission is provided between the input shaft and the intermediate shaft, and an intermediate cylindrical gear pair for power transmission is provided between the two adjacent intermediate shafts and the intermediate shaft and the output shaft. The output shaft has two parallel shafts, and the output cylindrical gear pair for power transmission and distribution is provided between the two output shafts.