Abstract: Twenty four crossbred ewes (Black-Suffolk♂× Small Tail Han sheep♀) were randomly allocated into three groups fed with different protein levels diet, medium protein (150 g·d^－1), low protein (112.5 g·d^－1) and high protein (187.5 g·d^－1) groups, respectively. The expression level of FAS mRNA in adipose tissue and muscle of sheep were quantified by RT-PCR. The result showed that expression of FAS mRNA decreased with the increase of diet protein level in abdominal subcutaneous adipose tissue, mesentery adipose tissue and semitendinosus muscle of sheep. But the expression of FAS mRNA had tissue specificity, it was expressed in abdominal subcutaneous and mesentery adipose tissue, there was no significant difference between medium protein group and low protein group (P>0.05), but the expression of high protein group was significantly lower than that of medium protein group and low protein group (P<0.05). While in semitendinosus muscle tissue, the expression of FAS mRNA in medium protein group was significantly different from that in high protein group and low protein group（P<0.05）, and the expression of FAS mRNA in high protein group was significantly higher than that in low protein group (P<0.01).