Dry spinning behavior of the segmented polyurethane‐urea elastometer/solvent binary system was studied theoretically and experimentally. Computer simulation was carried out by solving the partial differential equations numerically for discussing the structure and properties of as‐spun fibers. Spinning stress computed at the take‐up point was found to be useful for describing the segmental orientations and the aggregate structure of the hard segment in relation to the mechanical properties such as elastomeric character of the fibers. With increase of the spinning stress, orientation of the hard segment becomes higher. Orientation of the soft segment, however, is almost random regardless of spinning stress, resulting in the origin of the elastomeric character. Dependence of the spinning stress on the hydrogen bond concentration of urea group suggested that the aggregate structure of the hard segment was smaller when the fiber was spun at a higher spinning stress.