Abstract: In order to study the expression differences of early growth response 2（EGR2/Krox20） and insulin-like growth factor binding protein 5（IGFBP5） in the body side skin of Merino sheep and small-tailed Han sheep, and the correlation between Krox20 and IGFBP5 genes, and explore the relationship between Krox20 gene and wool curling, Three Merino sheep and three small-tailed Han sheep were selected as the study subjects. The immunohistochemistry, Quantitative Real-time PCR and Western-blot were used to detecte the expression of Krox20 and IGFBP5 genes and proteins in the body side skin of the two kinds of sheep. Sheep fibroblasts were cultured in vitro, and Krox20 gene was overexpressed by using pEGFP-N1 as carrier by cell transfection technique to analyze the relationship between Krox20 and IGFBP5 genes, and the relationship between Krox20 gene and wool curling was studied. The results showed that Krox20 and IGFBP5 proteins were strongly expressed in the secondary follicular hair matrix, inner and outer root sheath, epidermis, hair shaft and sebaceous gland in the body side skin of the Merino sheep and small-tailed Han sheep, and were weakly expressed in the dermal papilla. By optical density analysis, the expression levels of Krox20 and IGFBP5 proteins in the body side skin of Merino sheep were higher than those of small-tailed Han sheep, which were 1.78 times（P＜0.01） and 1.67 times（P＜0.01）, respectively. By qRT-PCR amplification analysis, the expression levels of Krox20 and IGFBP5 genes in the body side skin of Merino sheep were higher than those of small-tailed Han sheep, which were 2.44 times（P＜0.01） and 3.76（P＜0.01）, respectively. By Western blot analysis, the expression levels of Krox20 and IGFBP5 proteins in Merino sheep were higher than those in small-tailed Han sheep, which were 1.53 times（P＜0.01） and 1.42 times（P＜0.05）, respectively. After overexpressing Krox20 gene, the relative expression levels of Krox20 and IGFBP5 genes and proteins were significantly increased. The results indicated that Krox20 gene plaed a role in the formation of wool curling by affecting the expression of IGFBP5 gene.