Abstract: In many applications, the most important properties of spun yarns are their tensile characteristics. Therefore, the control of manufacturing processes inevitably requires knowledge of the mechanical behavior of textile materials in order to evaluate yarn strength during the various stages of manufacturing. We have analyzed the application of one of the most suitable model to characterize the viscoelastic properties of sizing yarns. Some modifications of the Standard Linear Solid (SLS) and Zurek models improve their ability to model viscoelastic behavior. Therefore, viscoelastic modeling based on mechanistic models for fitting experimental data of tensile tests was investigated. The rheological model of the sized yarn can be justified by considering the two models: the unsized yarn and the sizing film.