In order to improve the utilization of tobacco stem, the expanded tobacco stem granules were made through microwave expansion, granulation, and microwave size fixation. The physical structure, routine chemical components and volatile components of tobacco stem, expanded stem and granules made of it were measured. The results showed that: after expanding, the lamellar structure in stem disappeared and the cell cavity structure recovered; stem length changed a little, while its width and thickness increased significantly (P<0.001) by 83.56% and 115.56%, respectively. The natural bulk volume of stem increased significantly (P<0.001) by 257.53% on average, total sugar and reduced sugar decreased significantly (P<0.001 and P<0.01, respectively). Nicotine, total N, chlorine and potassium changed a little; the relative contents of 36 volatile aroma components changed significantly (P<0.001), most of them were furans.