Abstract: In order to clarify the chemical components, their contents and their harmony in different parts of flue-cured tobacco leaves so as to guide the accurate threshing in the primary processing, a single tobacco leaf area was divided into nine locations. The differences and characteristics of routine chemical components in the different locations were analyzed, and cluster analysis was carried out based on nine chemical components of flue-cured tobacco. The results showed that: 1) The contents (mass fraction) of the nine chemical components in the whole leaf of flue-cured tobacco was suitable and harmonious as a whole, however there were large differences in the chemical components and harmony indexes among the different locations after segmentation, and some indexes were significantly different among the different locations. 2) Nicotine content, total nitrogen content, ratio of sugar to nicotine and ratio of nitrogen to nicotine all increased from the leaf center to edge, while the contents of chlorine and potassium decreased. 3)Contents of nicotine, chlorine, total sugar and reducing sugar, ratio of sugar to nicotine as well as ratio of potassium to chlorine all increased from the tip to base, while the contents of potassium and total nitrogen decreased. 4) Based on the cluster analysis of chemical components, it was appropriate to divide a tobacco leaf into two broad locations from the lower third(close to the base) of the leaf.