Abstract: In order to investigate the key scorched odor components in the mainstream smoke of flue-cured tobacco, upper tobacco leaves with different levels of scorched odor(strong, medium, weak and none)were used to prepare single-level cigarettes. The flavor characteristics, types and releases of key volatile chemical components and the relationship between the two were analyzed and identified by sensory evaluation, gas chromatography-mass spectrometry (GC-MS), odor activity value (OAV) calculation and multivariate statistical analysis. The results showed that: 1) A total of 67 key odor components(OAV≥1)contributed to the overall aroma characteristics of the samples. 2)Based on integrated analysis of orthogonal partial least squares discriminant analysis(OPLS-DA), partial least squares regression (PLSR)and gradient boosting decision tree(GBDT), 23 key odor components were identified to have significant contributions to the scorched odor, including 2-(4-hydroxyphenyl)ethanol, 2-methyl-5, 6-diethylpyrazine, 3-hydroxybenzaldehyde, 3, 4-dimethyl-1, 2-cyclopentanedione, 2, 6-dimethoxyphenol, o-cresol, phenol, p-cresol, 2-propyl phenol, 3-hydroxyacetophenone, 2, 3-dimethylphenol, 2, 4-dimethylphenol, 4-ethylphenol, 3, 5-dimethylphenol, 2-methylbenzofuran, carvone, 4-isopropylbenzaldehyde, cinnamaldehyde, 2, 3-pentanedione, γ-nonalactone, furfuryl alcohol, 2, 3-butanedione and 2-methyl-3-acetylpyrazine.