Abstract: In order to find out the characteristics of chemical composition of tobacco stem and its relationship with the release of crotonaldehyde, the main chemical components in tobacco stem of 3 stalk positions (upper, middle and lower) from Chinese main tobacco growing areas and the release of crotonaldehyde were evaluated with correlation analysis. The results showed that the contents of starch, total alkaloid and total sugar in stem were lower than that in lamina. The contents of cellulose, potassium and pectin in stem were higher. The difference of the content of total sugar, starch, potassium, cellulose and hemicellulose among different growing areas was highly significant. The difference of the contents of the total alkaloid, lignin, pectin and the release of crotonaldehyde among different stalk positions was significant. The main chemical components in tobacco stem were obviously different from those in tobacco lamina. Growing area and stalk position were important factors that affect the chemical composition and release of crotonaldehyde. There was a significant positive correlation between the release of crotonaldehyde and the content of total sugar. The release of crotonaldehyde was negatively correlated with the contents of potassium and cellulose.