Abstract: To evaluate the characteristics of microwave expanded stem in cigarettes, microwave expanded stem was compared with traditional stem in terms of filling value, moisture retentivity, structural distribution, routine cigarette smoke chemical components, aroma components, cigarette sensory quality and mainstream smoke. The results showed that: Comparing with traditional stem, 1) the filling value of microwave expanded stem increased by 19.3%; the weight change of microwave expanded stem in dehumidification state was lower, indicating that the moisture retentivity of microwave expanded stem was higher, which was conducive to blending quality control and energy saving; 2) microwave expanded stem had better structural uniformity and stronger shatter resistance, which was conducive to stem blending uniformity and consumption reduction; 3) the total amount of aroma components in microwave expanded stem was higher, and the sensory quality of aroma and taste characteristics was better; 4) the releases of tar, nicotine and carbon monoxide from microwave expanded stem decreased by 0.90, 0.016 and 2.36 mg respectively, which could be used to control the releases of these chemical components.