Abstract: To reveal the characteristics and functions of tyrosine aminotransferase (TAT) gene family in tobacco, bioinformatics was used to identify and analyze TAT gene families from different tobacco varieties. The results showed that 4, 3 and 3 TAT genes were identified in the genomes of Nicotiana tabacum, Nicotiana sylvestris, and Nicotiana tomentosiformis, respectively. In subfamily Ⅰ, TATs were 1 263-1 338 bp in length, encoded 404-445 amino acids with molecular weights in 42.81-49.64 kD and the predicted TAT proteins were stable proteins with no transmembrane domains. In subfamily Ⅱ, the predicted TAT proteins were instable proteins. Except for NtabTAT4, the other TATs consisted of 7 exons and 6 introns. Phylogenetic analysis indicated that tobacco TAT proteins could be clustered into two subgroups: Group Ⅰand Group Ⅱ. qPCR showed that NtabTATs were expressed in roots, stalks, leaves and flowers.