Abstract: The uncoupling proteins 2 （UCP2） is one kind of protein which has uncoupling function. The general belief is that UCP2 is related to the fatty acid metabolism and ATP generation. The expression of UCP2 gene in different visceral tissues of small-tailed Han sheep at three age stages （6,8 and 10 months of age） was analyzed by real-time quantitative PCR technique. The result showed that ages did not affect the expression of UCP2 gene in the same visceral tissue （P〉0.05）;the expression level of UCP2 gene in spleen was significantly higher than that in heart, kidney and rumen （P〈0.05）, but there was no significant difference in heart, kidney and rumen （P〉0.05）. This experimental results support the fact of wide expression of UCP2 gene in visceral tissue of small-tailed Han sheep and the viewpoint that there is an association between UCP2 gene and the immunity. Furthermore, it is indicated that ages has little effect on the expression of UCP2 gene in the visceral tissue of small-tailed Han sheep at 6-10 months of age.