Abstract: In order to explore the regulation and control of gene expression about selenocysteine methyltransferase (SMT) the key enzyme related to selenium metabolism, the full-length DNA sequence and part promoter sequence of SMT were obtained using the technology of PCR and gene walking. The intron and promoter of SMT were analyzed by the tools of PLACE and PlantCARE to predicte its cis-acting element and function. The result showed that the full-length of SMT was 5473bp which contained 7 exons and 6 introns. The introns riched in light responsive elements, Hormone response element and resistance associated element. The promoter of SMT got by the method of genome walking was 375bp. In addition to the core promoter conserved elements of TATA-box and CAAT-box, there are many other important cis-acting elements as light response elements, low temperature response elements and endosperm specific expression elements and so on. The promoter cloning and structural analysis of key enzyme SMT gene related to selenium nutrition metabolism provided a theoretical basis for further revealing the biological function and regulation mechanism of SMT gene expression.