Abstract: The physiological and biochemical characters of a new flue-cured tobacco variety Zhongyan 203 during bulk curing process were studied with variety Zhongyan 100 as control. The results showed that the chlorophyll and carotenoid of Zhongyan 203 and Zhongyan 100 decomposed during curing. The decompositions in Zhongyan 203 were higher than in Zhongyan 100 at the end of curing. The ratio of carotenoid to chlorophyll in both cultivars increased first and then decreased. The ratio reached the peak at the end of 38 ℃ and 42 ℃ respectively. The ratio of carotenoid to chlorophyll of Zhongyan 100 was higher than that of Zhongyan 203 in yellowing stage but it was contrary in color fixing stage. The activity of PPO of Zhongyan 203 was consistently lower than that of Zhongyan 100 during curing. The starch content of the two cultivars showed decreasing trend, but the contents of total sugar and reducing sugar in general showed increasing trend. The starch content of Zhongyan 203 was lower than that of Zhongyan 100 during curing. Zhongyan 203 was beneficial to increase the accumulation of total sugar and reducing sugar. The content of protein of Zhongyan 203 was higher than that of Zhongyan 100 during curing. The content of phenolic compound and chlorogenic acid in the two cultivars changed similarly. From fresh tobacco leaves to the end of 47 ℃, the contents of phenolic compound and chlorogenic acid of Zhongyan 100 were higher than that of Zhongyan 203, but it was contrary from the end of 54 ℃ to the end of curing. The physiological and biochemical characters of Zhongyan 203 was better than that of Zhongyan 100 during curing.