The morphology and dimension of wool fibers were compared from the usually processed in the wool applications to investigate the relationships between shape and dimensions of wool and fuzzing and pilling of knitted fabrics. The frictional coefficients of wool fibers were measured by capstan method. The surface morphology were observed by scanning electron microscopy (SEM), and the cuticle scale edge height (CSH) were measured to verify the relationship between CSH and the differential friction effect (DFE). The hairiness and tensile properties of yarn were also reported. The pilling comparative experiments of the corresponding knitted fabrics were conducted with the ICI pilling box according to GBT 4802.3-2008. The pilling grades were estimated by numbers of pills. Experimental results showed that the CSH increased with the slenderness of wool fiber when the length is approximately equivalent. Specifically, the DFE increased distinctly as the CSH increased. The pills weight of wool knitted fabric was in good agreement with the CSH, DFE.