Abstract: Abstract: Forty one samples of sun air-cured tobacco leaves were collected from 9 provinces to analyze the relationship between chemical components and bitterness with correlation analysis, hierarchical cluster analysis and stepwise regression analysis. The results showed that leaves fromGuizhouProvince were the bitterest, leaves fromHeilongjiang, Shanxi and Hunan were bitter, andsamples from the other regions were less bitter. The bitterness degree of tobacco leaves was significantly positively correlated with cembranoid content, middle positively correlated with concentration of megastigmatrienone and rutin, while the other tested indicators were weakly correlated with the bitter taste of tobacco leaves.The content of cembranoidwas the main index affecting the degree of bitter taste thus can be used for the characterization, evaluation and prediction of the degree of bitterness of sun air-cured tobacco leaves.Content of rutin, megastigmatrienone(Ⅳ),megastigmatrienone(Ⅲ) were secondary indicators of the degree of bitterness ofsun air-cured tobacco leaves.