Abstract: Twenty four crossbred ewes (BlackSuffolk♂× Small Tail Han sheep♀) were randomly allocated into three treatments with different dietary CP levels (high protein， medium protein and low protein) respectively. The expression level of IGF-Ⅰ mRNA in adipose tissue and muscle of sheep were quantified by RT-PCR. The results showed that expression of IGF-Ⅰ mRNA increased with the increase of dietary CP level in abdominal subcutaneous adipose tissue， mesentery adipose tissue and semitendinosus muscle of sheep. The effects of dietary CP level on IGF-Ⅰgene expression showed tissue specificity. For abdominal and mesentery adipose tissues， IGF-Ⅰ mRNA expression increased with the increase of dietary CP level (P<0.05)， while the expression of IGF-ⅠmRNA in semitendinous muscle was significantly elevated only when the high protein diet was fed (P<0.01) and the difference of IGFⅠmRNA level between the medium and high protein treatments and between the medium and low protein treatments was insignificant (P>0.05).