A total of 111 samples in 2011 and 2012 was collected to study the variation of chemical constituents of various years, different grades and different cultivars of burnt-sweetness type flue-cured tobacco of Hunan. The re- sults showed that the total sugar, reducing sugar, sugar-alkali ratio and potassium-chloride ratio of tobacco leaves in 2012 were higher compared with 201l. Total nitrogen nicotine, potassium, chloride, starch and nitrogen-alkali ratio decreased. Differences in chemical constituents were significant or extremely significant am...