In this study,a full-length cDNA sequence of stachyose synthase gene was obtained from Brassica napus cultivar ‘Deyou 5’ for the first time using RT-PCR and RACE,named BnSTS (GenBank accession No.HQ285880.1).The full length of BnSTS is 3 210 bp,and the ORF is 2 619 bp,encoding 873 amino acids.Prokaryotic expression showed the recombinant plasmid can express the prospective proteins.Homology analysis of amino acid sequence of BnSTS showed the highest 82.08% similarity with STS from Arabidopsis thaliana.The Real-Time PCR indicated that gene expression level and the concentration of stachyose in different development stage of seeds were associated.Gene expression and the acquirement of desiccation tolerance of seeds had a time consistency trend,suggesting that the gene may play an important role in seed desiccation tolerance mechanisms.