Abstract: In order to compare the differences between shredded stem (SS) and cut stem (CS), the microstructure of SS and CS were characterized by scanning electron microscope (SEM) and mercury intrusion porosimeter. The combustion characteristics of the two types of tobacco stems were studied by a cone calorimeter. The influences of the two types of stems on cigarette's physical parameters and mainstream smoke were also investigated. The results showed that:1) SS was fiber-like and had a few slim holes, while CS was slice-like and featured macropore of 20-60 μm. 2) The specific pore volume, pore area, porosity and the most probable pore size of SS were smaller than those of CS. 3) At the early stage of combustion, the release rates of heat, CO₂, CO and the ratio between deliveries of CO and smoke of SS were lower than those of CS. However, the release rate of total smoke was the opposite. In the whole process of combustion, SS delivered more heat, CO₂, CO and less smoke than CS did. 4) At the addition rate of 20% in cigarette blend, comparing with cigarette containing CS, the draw resistance and ventilation rate were lower, the hardness was higher, CO/tar ratio decreased by 0.12, and CO delivery was selectively reduced by 12.7 percentage points for cigarette containing SS. In summary, there were obvious differences in microstructure and combustion characteristics between SS and CS, and the CO delivery and CO/tar ratio of cigarette containing SS were lower than those of cigarette containing CS.