Abstract: To clarify the influencing mechanism of curing methods on the composition and metabolism of amino acids in cigar filler tobacco, tobacco leaves of cv. Dexue No. 4 were cured by two curing methods, air-curing and flue-curing. The differences in contents of amino acids and composition between the leaves cured by the two methods were analyzed, and the non-targeted metabolomics of the cured leaves was studied using liquid chromatography-mass spectrometry (LC-MS/MS). The results showed that the aspartic acid content in air-cured leaves was the highest, accounting for 32.09% of the total free amino acid content, while the proline content was the highest, accounting for 70.84% of the total free amino acid content in flue-cured leaves. A total of 657 differential metabolites were identified at the yellowing stage of tobacco leaves from the two curing methods, of which 573 were higher in air-cured leaves. A total of 106 differential metabolic pathways were enriched and the metabolic pathway most affected by the curing method was amino acid biosynthesis. The contents of oxaloacetate and α-ketoglutarate, which are intermediates of the citric acid cycle in the metabolic synthesis of aspartic acid, glutamic acid, lysine and isoleucine, were higher in air-cured leaves than in that of flue-cured leaves. However, the content of 3-phosphoglyceric acid, which is the glycolytic metabolite of glycolysis in the metabolic synthesis of phenylalanine, cystine and serine, was higher in flue-cured leaves than in air-cured leaves. In conclusion, air-curing may affect the synthesis of amino acids in tobacco leaves by influencing the citric acid cycle pathway, whereas flue-curing may affect the synthesis of amino acids in tobacco leaves by influencing the glycolytic cycle pathway.