Abstract: To study the effects of air-curing time on aroma components, TSNA contents and smoking quality of flue-cured tobacco, flue-curing experiments were conducted in an electrothermal barn. Tobacco leaves were flue-cured after harvesting directly or after air-curing for 24, 48, 72, 96 hours, respectively. The contents of neutral aroma components and TSNAs in flue-cured tobacco leaves were determined, and the leaf sensory quality was evaluated. The results showed that with the prolonged air-curing before flue-curing, the contents of neutral aroma compounds increased, while sensory quality increased first then decreased. TSNA contents slowly increased at the early stage of air-curing, then the rate of increase speeded up significantly after 72 hours. Therefore, controlling the air-curing time before flue-curing within 48-72 hours is beneficial to improving the aroma component content and smoking quality and reducing the TSNAs content of flue-cured tobacco.