Abstract: Off-line pyrolysis-thermal desorption-GC-MS was applied to the determination of volatile components in tobacco and to the study of effects of some main saccharides (i.e., fructose, glucose and sucrose) on the component of volatile compounds in tobacco. It was found that: ① the main pyrolytic products of the saccharides obtained at high temperatures were furans, carboxylic acids and esters, and the pyrolytic products given by various saccharides were obviously different; ② when sucrose was added to tobacco, contents of aldehydes, ketones and N,S-containing heterocylcic compounds in the volatile components were remarkably increased; ③ when glucose was added, contents of alcohols, phenols and o-containing heterocyclic compounds were evidently increased; and ④ when fructose was added, only little changes in contents of the various components were observed, and in special even no change in content of o-containing heterocyclic compound was given. It was obvious that the saccharides not only underwent their own redox reactions, but also gave a series of chemical reactions with various components of tobacco, thus leading significant influence to the composition of the volatile components of tobacco smoke.