Abstract: Tobacco stem extract was inoculated with the aroma yeast and fermented at 30℃ for 2d. The content of chemical components in the extract after and before fermentation was determined. The results showed that the content of soluble sugar decreased remarkably especially glucose, and the acidic value increased after the fermentation, some volatile organic acids were produced. The glucose content decreased as the adverse factors, so in subsequent applications, glucose was needed to add. Compared with the unfermented extract, aroma components of tobacco stem extract fermented by the yeast to some extent was improved, the total aroma components after 48h fermentation increased 172. 13%.