The invention discloses a compound mill. A roller (1) is positioned on a base (8) through bearings (5), a cylindrical space is arranged inside the roller (1), one end of the roller (1) is closed by a stopper (2), the other end of the roller (1) is firstly provided with a tubular blank (4) and extends into a roll shaft (3) with an annular groove, a die comprises the roller (1), the stopper (2) and the roll shaft (3), the roller (1) drives the blank (4) to rotate at an angular speed 1 under the drive of external force, friction force is generated between the roll shaft (3) and the blank (4) by means of pressure P, and the roll shaft (3) rotates at an angular speed 2 and further has the functions of axial reciprocation and radial reciprocation. When the axis O2-O2 of the roll shaft (3) is misaligned with the axis O1-O1 of the roller, the blank (4) is embedded by the aid of offset, and the inner wall of the blank (4) is broached and shrunk in compound milling and extrusion, so that the blank (4) becomes a qualified workpiece with an external cylindrical surface and an internal annular groove. Afterwards, the roll shaft (3) radially returns, stops rotating and axially returns, the stopper advances (pushes the workpiece out of the roller) and returns, all technical processes for machining one workpiece are continued to be completed rapidly and automatically by means of mechanical, electrical and hydraulic integration, production efficiency is improved, labor intensity is reduced, chipless machining is realized, and metal materials are saved.