Abstract: S-adenosyl-methionine decarboxylase (SAMDC) is one of the key regulatory enzymes in the biosynthesis of polyamines. In this paper, using bioinformatics strategy and validating by experiment, a novel SAMDC of Salvia miltiorrhiza Bge was cloned and identified which was being blasted by search of Salvia miltiorrhiza expressed sequencetags (EST) database with homologous gene cDNA of Nicotiana tabacum. This sequence was confirmed by RT- PCR, molecular cloning and sequencing. Sequence analysis showed that the Salvia miltiorrhiza SAMDC (SmSAMDC) consisted of three open reading frames (ORFs) (tiny ORF, small ORF and main ORF), and the main ORF encoded 360 amino acids with a calculated molecular weight of 39.4 kD and isoelectric point of 4.71. Tertiary structure predicted that 25.28%, 24.17% and 50.56% amino acids composed a helix,extending strand and random coil, respectively. Alignments of deduced amino acid sequences demonstrated that the SmSAMDC had several highly conserved motifs in plant SAMDC family, including a putative pro-enzyme cleavage site a PEST sequence.