Abstract: In order to optimize the grading structure of flue-cured tobacco and promote industrial availability of upper leaves, a field experiment was conducted by using Yuyan No.6 to investigate the effects of removing unusable leaf at lower stalk position and spraying carbon dioxide trapping agent on the leaves on photosynthetic characteristics and metabolisms of carbon and nitrogen of upper leaves. In addition, chemical composition and economic traits of flue-cured tobacco leaves were also evaluated. The results showed that compared with the control (without removing lower leaves while topping), the leaf area, chlorophyll content, photosynthesis, metabolisms of carbon and nitrogen and total nitrogen contents of upper leaves, as well as the proportion of mid-to-high grade leaves were significantly increased. This was achieved by removing six lower unusable leaves while topping (Treatment 1), however the yield and output value of flue-cured tobacco leaves were decreased. Compared with Treatment 1, the leaf removing combined with spraying carbon dioxide trapping agent (Treatment 2) significantly increased the single leaf weight, the contents of potassium, total sugar and reducing sugar, total sugar/nicotine ratio, potassium/chlorine ratio, yield and output value of flue-cured tobacco leaves. Compared with the control, the leaf area, single leaf weight, potassium content, the proportion of mid-to-high grade leaves were increased by 11.53%, 23.19%, 12.69% and 17.50%, respectively. In general, Treatment 2 promotes the openness of upper leaves and the harmony of chemical compositions of flue-cured tobacco leaves and economic benefits.