Abstract: The cDNA sequence of senescence-associated gene (SAG) from Solanum tuberosum was acquired by electronic cloning. By using the methods of bioinformatics, we analyzed some characteristics of its encoded protein sequence. The results showed that the full-length of StSAG was 1 062 bp, which contained a 561 bp open reading frame encoding 186 amino acids. The isoelectric point of StSAG was 7.20, as a hydrophilic chloroplast protein without signal peptide. StSAG had 12 phosphorylation sites and a short extension peptide in the N terminal. The phylogenetic relationship between StSAG and Solanaceae plant was the closest.