Abstract: Sunflower seed husk with particle size of 0.154～0.28 mm pyrolysis weight loss behaviour was studied by thermogravimetric analysis(TG) at different heating rates (5, 10, 20, 30℃/min). Results showed that four stages appeared during pyrolysis process of the sunflower seed husk. At the same time, the starting and ending temperatures of each stage were slightly shifted to high temperature direction when the heating rates were increased. The activation energies of sunflower seed husk pyrolysis under different weight loss rates were centered on 140～178 kJ/mol by Ozawa law and Starink law. The expression of reaction mechanism function of sunflower seed husk pyrolysis was deduced through Coats-Redfern equation, Achar equation, and thermal analysis kinetic triplet comparative law. It was found that the experimental data were best described by the equation of Jander. The reaction mechanism was three-way uniformly spherical diffusion control. The reaction order was 2. The research provided a beneficial reference for the technological parameters optimization of biomass pyrlolysis.