Abstract: In order to develop key flavors for heated tobacco products, tobacco leaves from domestic and overseas were selected to prepare dry distilled flavor samples. The molecular distillation technology was applied to further refine flavor samples to obtain targeted light and heavy fractions. GC-MS and thermogravimetric analyses were used to investigate the differences in components and pyrolysis behaviors of the dry distilled flavor samples before and after molecular distillation. The results showed that: 1)Mass fractions of nicotine, pyridines, furfurals and ketones in the dry distilled flavor from Brazil leaf were higher, while those of furans and pyrones were lower. The dry distilled flavor samples prepared from Hunan, Henan and Yunnan tobacco leaves all presented higher mass fractions of characteristic components. 2)The light fractions obtained from the dry distilled flavor samples from Brazil and Yunnan tobacco leaves by molecular distillation contained greater mass fractions of nicotine and volatile aroma components, and could be thermal decomposed and released below 220 ℃ completely. The heavy fractions contained higher mass fractions of non-volatile components, and their corresponding thermal decomposition process was distributed in the temperature range of 110~350 ℃. 3)The applications of tobacco dry distilled flavor samples and their molecular distillation products promoted the sensory quality of heated tobacco products to a certain degree, mainly in the strength, aroma quality, aroma quantity and taste. The promotion effects of the light fractions were more significant, while the heavy fractions effectively improved the consistency of aroma during smoking.