Selenoprotein S (SelS), a member of selenoprotein family, plays important regulatory function in inflammation and metabolic diseases. SelS expression is up-regulated response to the inflammatory stimulus in many mammal cells, animal models as well as patients. In order to further understand the function of SelS gene, molecular characterization and transcriptional regulation of SelS from a Bama mini-pig were analyzed in the present study. The results showed that pig SelS encoded a protein of 190 amino acid with estimated molecular weight of 21.23 kDa and pI of 9.526. The genomic structure, promoter and deduced amino acid sequence were analyzed and found to share high similarity with those of human SelS. Pig SelS fusion protein was demonstrated to localize in the cytoplasm by fluorescence microscopy. Real-time PCR revealed the ubiquitous expression pattern of pig SelS in diverse tissues, a high level expression was observed in the liver and lung, relatively low expression in other tissues, especially in muscle. Promoter deletion analysis further suggests that an NF-κB binding site within the SelS promoter is responsible for the up-regulation of SelS transcription.