Abstract: The theory and method of fractal are applied to study the correlation between spinning finishes and PET staple fiber.The morphology and the frictional properties of oiled staple fibers are investigated from the point of their micro-structure and mechanism.By calculating the fractal dimensions of fibers with different oil pick up,the distribution of finishes on fiber surface is quantitatively evaluated,the complicated and non-linear process of the forming of oil emulsion drop size is elucidated,and the morphology of binary oil on the surface of PET staple fiber during different stages of spinning is judged.Therefore,the conditions of applying spinning finishes can be optimized and the risk of applied experiments can be lessened.