Abstract: To understand the function of tobacco glutathione transferases, a tobacco GST of tau class, previously known as NtParC, was identified by cluster analysis, and its protein activity was analyzed in vitro as well. The gene expression pattern under the treatment of topping, paraquat and mancozeb, was also investigated by qRT-PCR. The results showed that the tau class gene, renamed as NtGSTU17, was 666 bp in length, encoding 221 amino acids, which exhibited higher CDNB conjugation activity. NtGSTU17 was constitutively expressed in tobacco, while the expression level in root was a little bit lower than the level in aerial part of tobacco. Topping could increase NtGSTU17 expression. Mancozeb spraying significantly up-regulated the expression level of NtGSTU17 in a quick way both in root and leaf, in comparison with the significantly down-regulation effect of paraquat on the root. Therefore, NtGSTU17 might be involved in the tobacco stress response, and showed selectivity to different herbicides.