Abstract: 【Objective】To study the expression and potential functional role of ribosomal protein L8 gene(RPL8)in different tissues of Sewa sheep,and to reveal the molecular mechanism of RPL8 gene in regulating milk quality of Sewa sheep,so as to provide theoretical basis for promoting molecular genetic breeding of Sewa sheep.【Method】The RPL8 gene was amplified by PCR and its structure and function were analyzed by ProtParam,ProtScale,SignalP 5.0 and TMHMM 2.0 softwares. Real-time fluorescence quantitative PCR was used to detect its expression and distribution in various tissues of Sewa sheep.【Result】RPL8 gene was expressed in nine tissues of Sewa sheep,including mammary gland, muscle,heart,kidney,spleen,liver,small intestine,rumen and ovary,and the relative expression levels in small intestine,mammary gland and ovary were extremely significantly higher than those in other tissues(P<0.01). The coding region(CDS) of RPL8 gene in Sewa sheep was 774 bp in length,encoding 257 amino acid residues. The phylogenetic tree constructed based on the nucleotide sequence similarity of RPL8 gene showed that Sewa sheep was closely related to goat,yak,cattle and other ruminant species. The relative molecular weight of RPL8 protein was 28024.66 Da,and the theoretical isoelectric point(pI) was 11.04. RPL8 protein was a stable basic hydrophilic protein,without transmembrane structure,and mainly located in the cytoplasm(78.3%). There were 15 phosphorylation sites7 serine(S) sites,8 threonine(T) sitesin the RPL8 protein of Sewa sheep. The secondary and tertiary structure of RPL8 protein were mainly random coil. The interaction proteins of RPL8 protein from Sewa sheep were all ribosomal proteins,and the homology was as high as 99.90%. Among them,RPS5,RPS16,RPL11,RPS3,RPS18 and RPS11 belonged to the universal ribosomal protein family,and RPL13 belonged to the eukaryotic ribosomal protein family.【Conclusion】Sewa sheep RPL8 is an intracellular stable,basic,hydrophilic protein that has the basic structural features of a ribosomal protein. The expression of RPL8 gene is universal in all tissues of Sewa sheep,especially in the mammary gland and ovary,which indicates that RPL8 gene may not only play a basic role in its family function,but also affect milk fat content and periodic development of follicles in the mammary gland and ovary of Sewa sheep.