Abstract: In order to reveal the fragmentation/pulverization characteristics of Inner Mongolia lignite (X-L and B-L) during pyrolysis,the characterization index of particle fragmentation/pulverization was proposed. The effects of different pyrolysis conditions on particle fragmentation/pulverization were investigated by using laboratory fixed bed and fluidized bed experimental device. The results show that the particle size change rate and pulverization rate are 6.83% and 2.95% respectively under the separate thermal loading mode,and 2.72% and 1.54% respectively under separate mechanical force loading mode. Therefore,the particle size change rate and pulverization rate under the separate thermal loading method are higher than those under the separate mechanical force loading method. The total pore volume of the particles under the single thermal loading method is 4.34 times of that of raw coal,and the volumes of macropores and mesopores are greatly expanded,which verifies that the change of pore structure and particle size distribution of char is mainly related to the thermal force loading,while the mechanical force loading will only cause the particle surface to be broken. The particle size change rate is 9.76% and the pulverization rate is 5. 09% under the coupled loading of thermal and mechanical forces,which are higher than those under the loading mode of thermal or mechanical forces alone. The higher the content of volatile matter in coal is,the higher the yield of pyrolysis tar is,the higher the particle pulverization rate is. A function model of average particle size correlation before and after coal pyrolysis and fragmentation is established. The relative error between the model and the experimental value is small (The relative error corresponding to B-L≤3%,the relative error corresponding to X-L≤10%),which can predict the fragmentation/pulverization degree of lignite in the pyrolysis process.