Sulphonation reaction catalyzed by sulfotransferase (SOT, EC 2.8.2.–) plays a key role in plant growth and resistance. BnaSOT12a in Brassica nupus is a sulfotransferase gene, homologous to ATSOT12 in Arabidopsis. To seek BnaSOT12a gene functions associated with resistance, the gene expression level in various organs of Brassica nupus and the effect of overexpression on transgenic plant of Arabidopsis were analyzed. Results showed that BnaSOT12a could be expressed in leaves, buds and flowers. In flowers, the expression lever was the highest. However, no expression in stems and capsule. The endurable capability of NaCl was enhanced in root growth and germination in transgenic plant as BnaSOT12a overexpression in Arabidopsis. Nevertheless, sulphonation reaction catalyzed by BnaSOT12a did not affect disease-resistant signal transduction within Arabidopsis under salt stress. Hence, BnaSOT12a seems irrelevant with disease resistance pathway.