AOP3 is an important enzyme gene for secondary metabolism of glucosinolate side chain. In this study, the Brassica oleracea var. capitata AOP3 (BocAOP3) gene sequence was obtained from Brassica database (BRAD), and preformed for bioinformatics analysis. The analysis results indicated that BocAOP3 gene contains an open reading frame of 933 bp that encodes a 310 amino acid protein with a calculated molecular mass of 35.48 kD and an isoelectric point (pI) of 6.55. Secondary structure of protein indicated that BocAOP3 protein has 10 alpha helix, 13 beta sheet, and 25 beta turn and most amino acids are hydrophilic. Subcellular localization predicted BocAOP3 gene was in the cytoplasm. The conserved domain of the BocAOP3 protein is PLN02365. Homology analysis indicated that the BocAOP3 protein is apparently conserved during plant evolution. The results of this study provided a molecular basis for elucidating the BocAOP3 gene function in cabbage.