Abstract: In order to study the combustion and pyrolysis characteristics of tobacco celluloses with different structures, the celluloses were extracted from flue-cured tobacco, burley tobacco, oriental tobacco and tobacco stem, and their crystal structures were characterized. The combustion behavior and pyrolysis process of different types of tobacco celluloses were comparatively studied with thermogravimetric (TG) analyser and micro combustion calorimeter (MCC). The composition of pyrolysis products and the releasing behaviors of carbonyl compounds were measured by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and an off-line pyrolysis furnace. The results showed that:1) The cellulose structure of the different types of tobacco differed significantly, the cellulose of oriental tobacco had higher crystallinity, secondary fiber content, larger accessible fibril surface and fibril size. 2) The flammability of oriental tobacco cellulose was poor, its thermal stability was the worst at low temperatures ( < 350℃), however its carbon residue was the highest at high temperatures. 3) Tobacco stem cellulose produced more small molecular compounds, and the release of carbonyl compounds from oriental tobacco cellulose was slightly different with the other three tobacco celluloses. The structure differences of tobacco celluloses resulted in different combustion and pyrolysis characteristics.