The micro-level structure of staple yarn and the fiber arrangement inside it has a decisive influence on its physical properties. This study aims to introduce a combined method based on micro computerized tomography (micro CT) and digital image processing techniques to probe the ring yarn structure in a non-invasive manner. Two micro CT systems at different CT settings were applied to achieve optimal quality CT images of cotton ring yarns. Three image processing algorithms were proposed to enhance and process the yarn CT images in order to extract yarn structural information. The proposed method was also applied on two yarn specimens, which varied significantly in terms of their tensile strength, to study differences in their underlying structures. The results showed that the longitudinal arrangement of fibers in terms of their migratory behavior had a decisive influence on the tensile properties of the yarn. The stronger yarn showed a higher value of the amplitude and intensity of fiber migration compared to the weaker yarn, suggesting that the protocol established in this study can effectively reveal fiber arrangements within a staple yarn structure in a non-invasive manner.