The invention relates to a method for positioning yarn by an embedded system, belonging to the technical field of textile processing. The method comprises the technical proposal that: on a drafting mechanism of a ring spinning frame, two chopped fiber rough yarns unreeled from a rough yarn bobbin enter a drafting zone respectively in parallel to be drafted by yarn guiding horns; two continuous yarns are fed from the rear end of a front roller, and join with the two crude yarn strands respectively at a front jaw; the two drafted crude yarn strands and the two continuous yarns are output from the front jaw, enter a twisting triangular zone to be twisted, and are wound on a spun yarn bobbin into yarn; according to different relative positions of the two crude yarn strands and the two continuous yarns, yarns with various structures can be formed. The method can realize that polycomponent yarns with a core-spun structure, a fasciated structure and a folded yarn like structure can be spinned on the ring spinning frame; the yarn structure can be accurately selected and determined and is closer, and yarns has more excellent hairiness, brute force and evenness; and spinning of special fiber yarns on the traditional spinning equipment can be realized so as to enlarge the range of spinning materials.