The difference of aromatic components in the upper part and middle part of tobacco leaves was analyzed. Eleven different aromatic components, including solanone, dihydroactinidiolide and megastigmatrienone, were separated successfully through the HPLC-GC-MS system. Then eight aromatic components were selected as the major variants that caused the difference in tobacco odor by genetic algorithm. After that, a model that distinguishes the upper part and middle part of tobacco leaves was establishedby support vector machine. The accuracy of the proposed model, Leave-one-out cross-validations and the accuracy for forecasting unknown samples reached 88.65%, 84.40% and 82.86%respectively. Finally, Fisher discriminant vector method was used to distinguish the distribution of aroma on the upper part and middle part of tobacco leaves. The result shows that 3-hydroxy-$\beta $- dihydrogen ketone, megastigmatrienone and solanone were three major aromatic components that contribute to the difference in the upper part and middle part of tobacco leaves. This study is meaningful in that it provides help for tobacco leaves quality control and aroma control in the tobacco industry.