Abstract: To analyze and study the tensile properties and breaking features of the tri-component filament and staple fiber composite yarns, the yarns with different twists and different linear densities of each component were tested on a single yarn tester, and the tensile curves were plotted down. The experiments showed that generally there is a feature of multi-peak on the tensile curves of the tri-component composite yarns. The tensile curves of the composite yarns vary with the yarn twist. Moreover, the mechanical model is set up based on the practice of the yarn tension and the novel slider unit is introduced into the model. Its mathematic resolution can better explain the tensile property of the yarn.