The changes in pore structure characteristics of biomass particles during pyrolysis were studied.The samples were characterized by N2 isothermal adsorption/desorption method and scanning electronic microscopy (SEM).The results indicated that pyrolysis temperature had a notable impact on the pore structure and morphology of biomass char.Pyrolysis temperature was found to influence the size and the shape of char particles.A high temperature led to plastic deformation of particles resulting in smooth surfaces and large cavities.BET specific surface area first increased and then decreased.The change of pore volume was similar to that of BET specific surface area below 500℃.The fractal dimension (DFHH) calculated by fractal Frenkel-Halsey-Hill (FHH) equation could represent pore structure satisfactorily.The fractal analysis showed that pyrolysis temperature had a close relationship with DFHH.The fractal dimension could be correlated with BET specific surface area.