|Abstract:Recomsisted Tobacco sheet was increasingly used in cigarettes thanks to its low tar and nicotine in smoke. But there were some shortcomings in tobacco sheet, for example, it released wood odour in smoking, which affected the smoking quality of reconstituted tobacco. Therefore, we needed to study the structure of tobacco stem lignin(milled wood lignin, MWL), it could provide necessary academic basis for improving the mechanical properties and quality of reconstitued tobacco. The results showed that, the yield of MWL was 3.0%( based on dry raw materials), the extraction rate of MWL was 57.0%(the lignin contents of tobacco stem was 5.3%); The structure of MWL of tobacco stem was analyzed by FT-IR and 13C-NMR, the two types of structural unit for MWL of tobacco stem were mainly syringylreleased units and guaiacyl units. It was proved that β-O-4, 5-5, β-5 was probably the main type linkages between lignin, and the β-O-4 group and β-5 group were main groups.