Abstract: In order to investigate the organic acids in mainstream cigarette smoke, especially acidic aroma characteristics as tobacco flavors, and their distribution characteristics and sensory contribution, the tobacco and tobacco smoke components listed in The Chemical Components of Tobacco and Tobacco Smoke were used as the data source, and the organic acids were systematically screened based on their aroma contribution probability and the safety as tobacco additives. From the screened organic acids, a total of 21 organic acids with acidic aroma characteristics and tobacco flavor potential were defined. The releases of the 21 acids in mainstream smoke of cigarettes of 14 brands and their contents in total particulate matters (TPMs) were determined using N, O-bis(trimethylsilyl) trifluoroacetamide derivatization and GC-MS method. The olfactory thresholds of the 21 acids in ethanol were determined by three-alternative forced-choice (3-AFC) method, and their odor activity values (OAVs) in TPMs of mainstream smoke of 14 brand cigarette samples were calculated on the basis of their contents. The results showed that:1) In the mainstream smoke of conventional and low-tar Virginia type cigarettes, the levels of acetic acid, propionic acid and 2-oxopropionic acid were higher. In blended type cigarettes, the levels of acetic acid, propionic acid and 3-methylvaleric acid were higher. 2) The total contents of the 21 acids in mainstream smoke of blended type cigarettes were significantly higher than those of Virginia type cigarettes. 3) The contributions of isovaleric acid and acetic acid to the acidic aroma of mainstream smoke of Virginia type cigarettes were the most significant, and those of isovaleric acid, 3-methylvaleric acid and acetic acid to blended type cigarettes were the most significant.