SDG8 in Arabidopsis (AraSDG8) was confirmed to be a gene involved in the regulation of flowering time，but the role of SDG8 in Brassica rapa (BraSDG8 ) was unknown. In this work, full-length cDNA of BraSDG8 from Brassica rapa was cloned and analyzed. The BraSDG8 was 4 963 bp long encoding a polypeptide of 1 654 amino acids and three active domains which is similar to AraSDG8 (AWS domain, SET domain and Post SET domain) were observed in this peptide from amino acid residue 867 to residue 1 060. High similarity of gene sequence and peptide structure between BraSDG8 and AraSDG8 indicated that BraSDG8 may play an important role in regulation of flowering time in Brassica rapa.