The utility model discloses a round piece mould structure, include: the cushion, its fixed setting on the die holder subassembly, the cushion is seen from its longitudinal section and is isosceles trapezoid, the slider is seen from overlooking the angle, and the slider is whole to be circular, and the centre of a circle department of slider has offered the through -hole, and the cushion is located to the slider through the through -hole slip cap on, the inner wall of through -hole is the lateral wall assorted inclined plane with the cushion, first spring, it arranges along vertical direction, and first spring arranged along the circumference of slider a plurality of, the one end fixed connection die holder subassembly of first spring, relative other end fixed connection slider, second spring, its slant along being on a parallel with the inclined plane arrange, and the second spring arranged along the circumference of slider a plurality of, the one end fixed connection die holder subassembly of second spring, relative other end fixed connection slider. Compared with the prior art, the utility model, it can accomplish the material that takes off to round piece's the department of bending smoothly to effective machining efficiency who improves to this work piece.