In order to improve the curing quality and industrial availability of upper tobacco leaves, the effects of different temperature differences between dry and wet bulbs in yellowing stage on the chemical composition, aroma substances and economic characters of upper tobacco leaves were investigated using field test and indoor test. The results showed that when the dry bulb temperature was 38℃ and the temperature difference between dry and wet bulbs was 1.5℃, the coordination of chemical constituents and the content of aroma substances in the upper tobacco leaves were increased, the appearance quality and sensory evaluation quality were significantly improved, and the economic characters after curing were improved, thereby improving the yield and quality of the upper tobacco leaves.