Abstract: The effects of curing environment on the activity changes of amylase and starch phosphorylase in tobacco leaves during flue- curing were studied with the flue- cured tobacco cv. HD and K326. The results indicated that two peaks of amylase activity occured at the 36th and 72nd hour in curing respectively. The activity of starch phosphorylase was relatively higher in fresh leaves and reached its first peak at 24th hour in curing, followed by a valley at the 48th hour, and then the second peak at the 72nd hour. During the whole process of fluecuring,the activity of amylase and starch phosphorylase was relatively high in tobacco leaves with lower temperature and humidity yellowing, slow heating speed color- fixing, which were beneficial to the degradation of starch.