Abstract: In a field experiment, 3 tobacco-grown regions (Pingtang county, Dushan county, and Fuquan city) were selected to study the effects of foliar application of molybdenum on ascorbic acid (AsA) content and polyphenol oxidase (PPO) activity during earlier curing stage and quality of flue-cured tobacco leaves in different soils which lacked molybdenum. The results showed that molybdenum application could enhance AsA content in the upper mature tobacco leaves of different test sites, and AsA content was higher in treated leaves than in CK leaves in the earlier curing stage (0-90 h) in the mass. Molybdenum application could evidently reduce PPO activity, and PPO activity were lower in treated leaves than in CK leaves in the earlier curing stage (especially at 0-42 h). Molybdenum application could significantly improve chemical composition coordination of tobacco leaf, especially the upper leaf. Molybdenum application could increase the content of molybdenum, the percentage of fine grade tobacco and output value of tobacco leaves.