The invention discloses metal fiber and a roller for blended yarn. The roller is used for rolling the metal fiber, the roller is in a cylindrical shape, and a plurality of wheel teeth are arranged on the periphery of the roller; the tooth height of each wheel tooth is the same, and the wheel teeth are arranged to be perpendicular to the axial direction of the roller, the outlines of the tops of the wheel teeth are first circular arc sections, the outlines of wheel tooth sockets are second circular arc sections, the first circular arc sections and the second circular arc sections have the same curvature radius, the outlines of the tooth profiles of the wheel teeth are first linear sections, and the first linear sections are tangent to the first circular arc sections and the second circular arc sections. The metal fiber in specific shapes manufactured through pressing of the roller can obviously improve the uniformity and fastness of fiber, and the probability of the metal fiber being pressed to be broken in the pressing process of the roller is reduced by over 70%.