Abstract: In order to study the pulverization characteristics of lignite under pyrolysis conditions, the pyrolysis of two lignites from Xilinhaote and Baorixile with size sof0.5 ~ 6.0 mm were studied in a mini-fixed bed reactor. The test influential parameters included particle sizes, final temperature, heating rate and residence time of particles were conducted. The following results showed: with the decrease of the grain size of the two kinds of lignites, the total mass fraction of the primary particle an d the lower particle of the semi coke increased from 89.62% to 99.49% and 77.11% to 99 .53% respectively; the pulverization degree of two lignites increased with incre ases in the particle sizes, final temperature, heating rate and residence time of particles. The gray relational analysis showed that the heating rate and particle sizes we re the major influencing factors, but the influence of residence time was not significant on the pulverization of lignite during pyrolysis. The correlation model of average particle size before and after pulverization was established, and it was proved that the change of particle size could be predicted well.