Abstract: 150 wool samples including 3 types of fineness(≤18 μm，18～20 μm and ≥20 μm) were taken, and the variations of fiber diameter along and within staple were studied. The results demonstrate that the variation of fiber diameter along staple is similar in different types of fineness and agrees with the seasonal change of feedstuff, and the wool with fineness being less than 18 μm has the least variations of fiber diameter（P<0.01）; Contrarily, the variation of diameter between fibers within staple is increased in company with the reducing of fineness（P<0.01）.

Key words: fine wool; fiber diameter; variation