Abstract: The photosynthetic characteristics of flue-cured tobacco cultivar G80 were systematically studied. The results showed that 1)light saturation point, net photosynthetic rate, light compensation point, apparent quantum yield, CO₂ saturation point and respiratory rate were increased with the leaves growing, the values reached their maximum at fast-growing stage and then decreased gradually with the leaves ripening, and 2)CO₂ compensation point was increased all the time. There wasn't obvious photosynthetic midday depression in G80 leaves. The photosynthetic rate of the leaves exposed to high CO₂ atmosphere for half an hour was obviously decreased.