Abstract: In the present study, we collect coal samples in Wudong coal mine which are situated in the middle part of Southern Junggar coalfield.The coal samples (0.15-0.18 mm) are divided into ten parts which treated by heating for about twenty minutes in different temperature (from 50℃ to 500℃ with interval of 50℃) in muffle oven.SEM, XRD, IR and TG are employed to investigate the kinetics.The results show that the surface increases with the decrease of the particle size.The middle-size pores and cracks increases with the increase of the temperature experienced.The coalification of different sizes coal samples stays unchanged.And the coalification of coal samples which experienced different temperatures show a fluctuation of change (peak at 450℃ and bottom at 350℃).The higher of the coalification of coal, the more developed of microcrystalline structure of it which indicates the more prone of coal spontaneous combustion.The results from infrared spectra analysis show that the OH- functional group decreases with the decrease of particle size, meanwhile the CH- functional group increases.With the increase of the experienced temperatures, OH- functional group,-CH₂-CH₃ functional group decreases, CH- functional group increases.Different oxygen functional groups have a fluctuated change with the increase of experienced temperatures.With the increase of the temperatures, the characteristic temperature T₁ and T₂ stay stable without noticeable changes.The T₃ and T₄ increase during this process except the T₅.The activation energy of experimental coal samples decreases.With the increase of experienced temperature, coal samples' activation energy shows a trend of fluctuation.