Abstract: In order to evaluate the quality of blending and threshing modules with robust flavor style, the contents of non-volatile organic acids in flue-cured tobacco in 33 multi-grade blending and threshing modules with different flavor styles were determined and analyzed by Orthogonal Partial Least Squares Regression Discriminant Analysis (OPLS-DA). The results showed that:1) There were significant differences in the content of non-volatile organic acids among the tobacco leaves used in the blending and threshing modules for different flavor styles. The contents of oxalic acid, malonic acid, succinic acid, malic acid, citric acid and linoleic acid and the total content of non-volatile organic acids in the modules with robust flavor style were significantly higher than those with fresh or medium flavor style. 2) The OPLS-DA model based on non-volatile organic acids had a good simulation effect, and the parameters, R²X, R²Y and Q², of the model were 0.770, 0.774 and 0.627 respectively. 3) The scores of two principal components obtained by the model could well distinguish the tobacco leaves in the modules with different flavor styles. 4) Six non-volatile organic acid indexes with VIP value higher than 1 were screened by the model, which contributed more to the variable explanation. The six indexes in the correlation degree with tobacco leaves in the modules with robust flavor style were citric acid, malonic acid, malic acid, linoleic acid, succinic acid and oxalic acid. In conclusion, there were significant differences in the non-volatile organic acids among the tobacco leaves used in the blending and threshing modules with different flavor styles, and the six indexes (citric acid, malonic acid, malic acid, linoleic acid, succinic acid and oxalic acid) selected by the model can be used as the characteristic indexes to distinguish the tobacco leaves with robust flavor style.