Abstract: there were significant differences in leaf color between different cigar tobacco varieties after air-curing. In this study, the non-targeted metabolomic analysis was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to investigate the relative abundance of metabolites and their relationship with the differences in leaf color after air-curing of cigar tobacco varieties Chuxue No. 10 (CX-010) and Chuxue No. 14 (CX-014). The results showed that there were significant metabolite abundance differences between tobacco leaves of the two varieties after air-curing. Compared with CX-014, the relative abundance of free amino acids and alkaloids in CX-010 tobacco leaves was generally lower, and the overall lipid content was higher. 32 different metabolites with the largest difference in difference multiplicity contained 2 amino acids, 10 phenolic acids, 3 amides and other substances. Combined with the analysis of the KEGG metabolic pathway, it was found that the proline biosynthesis pathway in the arginine and proline metabolic pathways differed significantly between the two varieties. The physiological function analysis of the differential metabolites showed that the differences in leaf color between the two varieties after air-curing might be mainly related to the differences in the contents of proline, salicylic acid, and flavonoids and alkaloids.