The invention relates to a drafting device capable of realizing mixed feeding of different raw materials on a spinning frame, and belongs to the technical field of textile processing. The invention adopts the technical scheme that: the surface of a middle leather roller of a drafting mechanism is provided with positioned annular single grooves or positioned annular double grooves at different positions along the circumferential direction, an upper leather ring is sleeved on the surface of the middle leather roller, a lower leather ring is sleeved on the surface of a middle roller, a positioned yarn feeding device is arranged in back of the drafting mechanism of the spinning frame, the positioned yarn feeding device is provided with positioned yarn feeding holes corresponding to the positioned annular grooves on the middle leather roller, the positioned yarn feeding device is also provided with one or more yarn feeding holes, and the positioned yarn feeding holes and the yarn feeding holes are on the same horizontal line. The drafting mechanism of the spinning frame provided by the invention can change the feeding and drafting forms of the conventional spinning frame and adapt to simultaneous feeding and drafting of a plurality of rove strands consisting of single-component fibers of different categories.