Abstract: At present, the maturity can not reach the required standard has become an important factor limiting the quality promotion of upper leaves of flue-cured tobacco in some areas of China. In order to reveal the ripening mechanism so as to effectively regulate the maturity of upper leaves, the metabolic rules of carbohydrates, nitrogen-containing compounds, aroma substances and plastid pigments in the ripening process of upper leaves were comprehensively summarized. The change rules of enzyme activity, metabolism-related genes and protein function during the ripening process of upper leaves were discussed. Based on the researches and application status of the maturity of upper leaves, the future hot topics were prospected, including the ripening mechanism, the judgment of maturity characteristics and the use of growth regulators.