W12 series of four-roller rolling machine. The rotation of top roller adopts mechanical transmission; the up-and-down movement of bottom roller and side roller adopts hydraulic transmission; the machine operation adopts concentrated electric control. This machine can complete multiple operations including pre-bending both ends of plate material, rolling barrel body, and arcing work-piece during a time of loading material. This machine can also make a certain degree of shaping and leveling for metal plate material. It has the function of directly pre-bending to improve efficiency and save materials.