Abstract: Based on the precursors' study,the experiment of heating-up and oxidation of the 2nd coal in Xuecun coal mine was taken,and the concentration of the gas which was generated by oxidation was determined.The exothermic quantity of coal oxidation was computed according to the bond energy of the generated gas,and the specific heat of coal at different temperature was measured by the DSC experiment.The time which reach to the critical temperature of coal spontaneous heating-up was computed by different temperature segment,and the shortest spontaneous combustion time was determined,it is almost in accord with the results with statistics.