Abstract: To investigate the influence of particle size on spontaneous combustion characteristic of coal, by taking No.8 coal in Liuzhuang Coal Mine as the research object, the programmed temperature experiment of coal samples with different particle sizes was carried out, and the relationship model of oxygen consumption rate, gas product generation rate and temperature and particle size of coal samples was established. The results indicate that the oxygen consumption rate and gas product generation rate of coal sample decreases linearly first and then rapidly with the increase of coal particle size, and the higher the temperature, the greater the influence of particle size on coal spontaneous combustion characteristic parameters. When the particle size of coal sample increases from 0.125 mm to 0.425 mm, the critical temperature of coal sample decreases from 80 ℃ to 60 ℃, and the dry cracking temperature decreases from 120 ℃ to 110 ℃. The activation energy before the critical temperature gradually increases with the increase of particle size, but the larger the range of mixed particle sizes, the activation energy decreases correspondingly. The change law of coal activation energy after the cracking temperature is opposite to this. In a certain range of particle size and temperature, the variation of oxygen consumption rate and gas product rate of coal sample with particle size and temperature can be described by 2D Gaussian function distribution.