Abstract: Wool diameter is the key factor affecting wool prices, and is also the most important indicator of the wool industry requirements. The present study analyzed the wool diameter of Erdos fine wool sheep, and on this basis, the skin transcriptome of different fiber diameter individuals were sequenced using high-throughput sequencing technology. The results showed that the fiber diameter of Erdos fine wool sheep is between （13.16±3.39）-（27.81 ±5.63）μm, with the coefficient of variation of half the samples between 18.7%-23.3%; the fiber diameter of bred males or ewes is smaller than that of adult males or ewes （P〈0.01）; an amount of 28.6 G data were obtained from six individuals through skin transcriptome sequencing, which laid foundation for the selection of wool diameter-related zenes.