Abstract: This trial was carried out to seek after the curing craft of middle-upper leaves of flue-cured tobacco, and to improve curing quality of the leaves. The result indicated that, It takes longer time over curing on 42℃and 54℃ with ‘wo-prolonged one-low’ curing mode than with conventionality curing mode. The activity of various enzymes in tobacco leaves is sustaining high and is on behalf of degradation of big molecule matter. Chemic elements of cured tobacco are comparatively harmony, reducing sugar content is relatively high, and starch content is low. Appearance quality of cured leaves is improved evidently with no cyan vein by and large. The classy cutters rate is increased by 13.34 percentage，and mean price increased by 0.46yuan/kg.The classy upper leaf rate is increased by 21.33 percentage，and mean price increased by 0.85 Yuan/kg. However，the cost of expended energy is increased appreciably with “two-prolonged one-low” curing mode.