Tannins biodegradation by a microorganism is one of the most efficient ways to produce bioproducts of high value. However, the mechanism of tannins biodegradation by yeast has been little explored. In this study, T9 isolated from red wine starter showed the ability for tannins degradation and had its highest biomass when the initial tannic acid concentration was 20 g/L. Furthermore, the genes involved in the tannin degradation process were analyzed. Genes , and encoding three different tannases respectively were identified in the T9. Among these genes, and can be induced by tannin acid simultaneously at both gene transcription and protein expression levels. Our assay result showed that the deletion of and resulted in tannase activity decline with 51.3 ± 4.1 and 64.1 ± 1.9 U/mL, respectively, which is much lower than that of T9 with 91.3 ± 5.8 U/mL. In addition, another gene coding gallic acid decarboxylase () was knocked out to better clarify its function. Mutant completely lost gallic acid decarboxylase activity and no pyrogallic acid was seen during the entire cultivation process, confirming that there was a sole gene encoding decarboxylase in the T9. These results demonstrated that , and were crucial for tannin degradation and provided new insights for the mechanism of tannins biodegradation by yeast. This finding showed that has potential in the production of tannase and metabolites, such as gall acid and pyrogallol.