Abstract: To eliminate the interference of calcium phosphate on the determination of calcium carbonate in reconstituted tobacco and to develop an accurate method for determining the mass percentage of calcium carbonate, CO₂ was applied to react with calcium carbonate in reconstituted tobacco samples to form water-soluble calcium bicarbonate. Following the treatment, the variation of calcium ion concentration after CO₂ treatment was determined by ion chromatography to analyze the mass percentage of calcium carbonate. The feasibility of the method was verified based on the repeatability, recovery, limit of detection (LOD), and limit of quantification (LOQ). The results showed that: 1) Calcium carbonate could be separated from calcium phosphate by CO₂ treatment, and the mass percentage of calcium carbonate in the reconstituted tobacco samples could be accurately determined using three different pretreatment methods. 2) This method showed better repeatability and recovery with a relative standard deviation (RSD, n=5) of 2.69% and recoveries in the range of 95%-102%. The LOD and LOQ were 0.12% and 0.39%, respectively. 3) The variation of the mass percentage of calcium carbonate in different reconstituted tobacco samples was large and varied from 2% to 4% in five reconstituted tobacco samples. In conclusion, this method was convenient, rapid, and suitable for accurate determination of the mass percentage of calcium carbonate in reconstituted tobacco and other complex calcium salt reconstituted tobacco systems.