Abstract: A method to determine the calcium carbonate content in reconstituted tobacco was established using thermal analysis technology. This method measured the characteristic peak of thermal decomposition of calcium carbonate and quantified the mass loss of carbon dioxide in the pyrolysis process. The matrix interference was verified by standard addition method. The recoveries of the thermal analysis in nitrogen and air atmosphere were measured, and the test results were compared with those obtained by a classical ion chromatography. The results showed that:1) The pyrolysis peak of calcium carbonate in reconstituted tobacco sample A was located at 870-980 K, and the mass loss of carbon dioxide corresponding to this temperature range was 3.62%, which converted into 8.23% calcium carbonate content. 2) The correlation coefficient of the standard curve obtained by the standard addition method reached 0.999, and the calcium carbonate content in sample A was 7.59% by standard curve extrapolation method. The relative deviation between the results of the two method was 7.8%, which indicated that the reconstituted tobacco substrate had little interference on the thermal analysis result. 3) The spiked recoveries of calcium carbonate in nitrogen and air atmosphere were 97.50%-102.63% and 60.71%-85.95%, respectively, which suggested that the accuracy of the results obtained in nitrogen atmosphere was higher. The method had a good stability with the variation coefficient of 0.76% by 5 repetitive tests of the same sample. 4) The calcium carbonate contents in reconstituted tobacco samples A and B obtained by the thermal method were slightly lower than those by the ion chromatography with the absolute values of deviation less than 0.4 percentage points. However, the thermal analysis method was simple, fast, convenient, and environment-friendly with no reagent needed in experimental processes.