Abstract: In order to investigate the variations of soil respiration rate during flue-cured tobacco growth period and carbon balance of tobacco field ecosystems, a closed chamber technique (infrared CO₂ analyser) was used to determine variations of respiration rate of the ridge soil, the ridge soil without roots (soil microbial) and the soil between ridges.The contribution of root respiration to the ridge soil respiration was analyzed and the carbon balance of tobacco field ecosystems was estimated. The results showed that during the flue-cured tobacco growth period, the ridge soil respiration was affected by flue-cured tobacco growth and soil temperature, displaying a significant seasonal variation. During the early growth period, the soil respiration rate increased slowly, and then it increased gradually, with a peak occurring on the 107th day C 256.8 mg/(m²·h) after tobacco seedling transplanting. Seasonal variation of respiration rate of the ridge soil without roots and the soil between ridges was not significant. The order of Q₁₀ value of soil temperatureat 10 cm depth with the ridge soil respiration with its components and respiration of the soil between ridges was root respiration>the ridge soil respiration>soil microbial respiration> the soil between ridges respiration. During the whole growth period, the contribution of root respiration to the ridge soil respiration was 44.2%, while the soil microbial respiration was 55.8%. In the flue-cured tobacco fields, the net primary productivity carbon was C 2975.9 kg/hm², and soil heterotrophic respiration to release carbon was C 1409.1 kg/hm² and the net ecosystem carbon budget was C 1566.8 kg/hm².