Abstract: In view of the fertilization measures of flue-cured tobacco, the carbon budget of flue-cured tobacco ecosystem was studied to provide basis for improving carbon management in tobacco fields and calculating carbon sink in farmlands. Based on the long-term positioning experiment in Longgang, Guizhou Province, four experimental treatments were selected in 2015-2017, including no fertilizer (CK), single fertilizer (NPK), fertilizer with manure (NPK+M), fertilizer with bio-organic fertilizer (NPK+ BM), to study the carbon accumulation and CO₂ emission of the flue-cured tobacco ecosystem. The results showed that long-term application of chemical fertilizers can significantly improve the carbon assimilation of tobacco. The carbon accumulation of the NPK treatment is significantly higher than CK, being 3.09 times of CK. Compared with the NPK treatment, the carbon accumulation of NPK+M and NPK+BM increased by 2.7% and 12.43%, respectively. Fertilization increased the distribution ratio of stem carbon, reduced the distribution ratio of leaf carbon, but had no significant effect on the root carbon ratio. The CO₂ emission of non-fertilization treatment was 7 194.58 kg/hm², which was increased by 22.99% compared with that of the non-fertilization treatment. The CO₂ emission of the manure combined with fertilizer treatment was higher than that of the single fertilization treatments, and the CO₂ emission of the NPK+M treatment was 23.65% higher than that of the NPK treatment. The ecological efficiency of carbon under the fertilization treatments was significantly higher than that of the non-fertilization treatment. With no fertilization, the flue-cured tobacco ecosystem is the carbon source to atmospheric CO₂. With single fertilization, the carbon sink is 132.65 kg/ha in the flue-cured tobacco ecosystem. The carbon sink of the organic fertilizer and bio organic fertilizer treatments are 869.40 kg/ha and 740.99 kg/ha, respectively. Single application of chemical fertilizers can promote the carbon accumulation of flue-cured tobacco, improve the carbon ecological efficiency, and make the tobacco field ecosystem a “carbon sink” for the atmosphere; Combined application of organic and inorganic fertilizers can increase the external carbon, and improve the carbon sink of the flue-cured tobacco ecosystem.