Abstract: To clarify the material transformation patterns and metabolite differences in upper tobacco leaves of flue-cured tobacco from different flavor type growing areas during the maturation process, tobacco leaves from three regions including Henan (robust flavor type), Guizhou (medium flavor type) and Yunnan (fresh flavor type) were selected as research subjects. The upper tobacco leaf samples were collected every 7 days after topping and analyzed by GC-MS in combination with Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) and Hierarchical Cluster Analysis (HCA). The results indicated that the ripening periods for the upper tobacco leaves of the robust, medium and fresh flavor types were 80, 52 and 45 days after topping, respectively, with the robust flavor type leaves ripening significantly longer in the field. Based on the metabolite composition, the maturation process of the upper tobacco leaves could be roughly divided into three stages, namely early, middle and late maturation. Analysis of differential metabolites at the three stages of maturation showed that 76, 63 and 44 differential metabolites were identified for the leaves of robust, medium and fresh flavor types, respectively, and the key metabolic pathways involved were 12, 17 and 10 for the leaves of three flavor types. The core metabolic pathways common to all three flavor type leaves included galactose metabolism, fructose and mannose metabolism, alanine, aspartate and glutamate metabolism, glutathione metabolism, pentose phosphate pathway, and glycine, serine and threonine metabolism. In addition, anatabine, phytol and scopolamine was considered to be the key metabolites during the maturation of upper tobacco leaves of the robust flavor type; alpha-tocopherol could be the key metabolite for upper tobacco leaves of the medium flavor type; and D-rhamnose, scopolamine and L-lysine were the key metabolites for upper tobacco leaves of the fresh flavor type.