The invention relates to a machining device for functional yarns. The machining device comprises a drafting system and a twisting system. A nozzle device is arranged in back of a front roller of the drafting system; a pair of output rollers in front of the twisting system are arranged in back of the nozzle device; the nozzle device comprises a suction opening, an air inlet tube, a yarn path and a fiber opening pipe; the suction opening is a three-opening ring-shaped horn mouth; the three-opening ring-shaped horn mouth comprises a horn mouth inner ring provided with an inner ring opening and a horn mouth outer ring provided with an outer ring opening; the inner ring opening and the outer ring opening are communicated with opening gaps arranged on the lateral face of the nozzle device; one end of the air inlet tube is connected with the suction opening, and the other end of the air inlet tube is connected with the yarn path; spray holes communicated with an air chamber are arranged on the outer circumference of the air inlet tube, and are configured along a tangent direction of the inner wall of the yarn path; and the yarn path is connected with the fiber opening tube. With the adoption of the machining device provided by the invention, different kinds of fibers are located at special positions of a yarn inner layer and a yarn outer layer, so as to obtain the functional yarns.