Abstract: Curing experiments were conducted with upper leaves of NC89. Chlorophyll, carotenoid, starch, reducing sugar, protein, nicotine, and flavoring substances in the leaves were determined, and appearance ripeness of the leaves was also investigated during the curing process. The results showed that the transit time had a great effect on the after-ripening of the upper flue-cured tobacco leaves. The after-ripeness and usability of the leaves were improved by selecting the best transit time in flue curing.