Abstract: In order to investigate the effects of tobacco size on its pyrolysis and combustion properties, tobacco strands of different widths and tobacco powder were tested by a macro-thermogravimetric analyzer. The kinetic parameters of the samples at different pyrolysis/combustion stages were calculated by Coats-Redfern method. The results showed that:1) The maximum weight loss rate of tobacco powder was significantly higher than that of tobacco strands. Within the test range of 0.8-1.2 mm, the strand widths did not affect weight loss rate obviously. 2) The devolatilization and combustion of three biomass components (hemicellulose, cellulose and lignin) in tobacco powder combined into one peak in DTG curves, rather than three independent peaks in those of tobacco strands. 3) Tobacco powder featured higher light-off temperature and significantly lower burn-out temperature than those of tobacco strands. The combustion characteristic indexes of tobacco powder was 4.75×10^-7%²·min^-2·℃^-3, that of tobacco strands ranged from 2.63×10^-7 to 2.99×10^-7%²·min^-2·℃^-3, negatively correlated to cut width. 4) The pyrolysis kinetic analysis of Coats-Redfern method indicated that the pyrolysis of tobacco powder was mainly controlled by a second-order chemical reaction in Zone 2 within the pyrolysis temperature range of small molecule organic matter, while the pyrolysis of tobacco strands was dominated by a three-dimensional diffusion. The samples of flue-cured tobacco of smaller size features better combustibility, and the thermal conversion reaction of tobacco strands was influenced more significantly by its resistance to heat and mass transfer.