The drawing process in staple yarn manufacturing has the object to increase the regularity of sliver linear density on the basis of the probability by doubling and to improve the orientation of fibers along the sliver axis. This process plays an important role in the quality of the spun yam, because the drawn sliver has no more opportunity to improve the regularity in the next processes in spinning. Therefore new drawing frames are equipped with automatic sliver irregularity control system which is called autoleveller. But an optimal control needs the dynamic characteristics which can be expressed in the form of a mathematical model. For identification of dynamic characteristics, the structure of the model must be known. In this study, it is attempted to ascertain the structure of the mathematical model of the dynamic characteristics of drawing which is not revealed yet. As results can be shown that 1) for the on-line measurement of the sliver irregularity, a leafspring with strain gauge has functioned electively, 2) the characteristics of the output sliver linear density for the input sliver could be expressed in the form of a proportional derivative system with time delay of the 1st order, where the behavior of the output sliver linear density to the draft ratio change in the form of a proportional system with time delay of the 1st order.